Hunink, M.G.M.

Impact of secondary cardiovascular events on health status (Article)

2012-01-01T00:00:00Z

Objectives: Estimates regarding the impact of secondary cardiovascular events on health status in patients treated for cardiovascular disease are scarce and of limited accuracy. Methods: We obtained individual patient data on health status (EuroQol five-dimensional questionnaire) and secondary cardiovascular events (death, myocardial infarction, cerebrovascular accidents, amputation, extracranial bleeding, and reinterventions) observed during 12 to 36 months of follow-up. Data originated from five completed clinical trials on revascularization in coronary heart disease (n = 2593) or peripheral arterial disease (PAD; n = 1379). We used linear mixed-effects modeling to estimate the acute impact of the initial secondary event and the health status before and after the event. Results: A total of 1595 patients had at least one secondary event. Loss of health status just before the event ranged from 0.36 utility score for amputation in women with PAD to zero for cerebrovascular accident in men with PAD. In patients with coronary heart disease, pre-event health status loss ranged from 0.34 for extracranial bleeding in women to 0.10 for myocardial infarction in women. The acute impact of secondary events ranged from minor deterioration for cerebrovascular accident (-0.03) to improvement after all other events, ranging from +0.01 for occlusion to +0.22 for amputation. Women had significantly lower pre-event scores than did men: -0.04 to -0.10 in coronary heart disease and -0.04 to -0.27 in PAD. Older patients had mostly large but insignificantly lower pre-event scores than did younger patients (range +0.04 to -0.67). Conclusions: Secondary events after revascularization in patients with cardiovascular disease are associated with health status loss before the event, while acute impact of the events was mostly small.

Quantifying the benefit of early living-donor renal transplantation with a simulation model of the Dutch renal replacement therapy population (Article)

2012-01-01T00:00:00Z

Background.Early living-donor transplantation improves patient-and graft-survival compared with possible cadaveric renal transplantation (RTx), but the magnitude of the survival gain is unknown. For patients starting renal replacement therapy (RRT), we aimed to quantify the survival benefit of early living-donor transplantation compared with dialysis and possible cadaveric transplantation and to estimate the population benefit from increasing the early transplantation rate. Methods.We used a decision-analytic computer-simulation model, with a lifetime time horizon, simulating patients starting RRT, using data from the Dutch End-Stage Renal Disease Registry and published data. We compared the (quality adjusted) life expectancy (LE) of 'early living-donor RTx' and 'dialysis' (with possible cadaveric RTx if available). Results.LE and quality-adjusted LE benefits of the early living-donor RTx compared with the dialysis strategy for 40-year-old patients ranged from 7.5 to 9.9 life years (LYs) [6.7-8.8 quality-adjusted life years (QALYs)] depending on the primary renal disease. For 70-year-old patients, the benefit was 4.3-6.0 LYs (4.3-6.0 QALYs). Increasing the early transplantation rate from currently 5.8 to 22.2% (the highest in Europe) would increase average LE by 1.2 LYs and total LE for annual incident cases in the Netherlands by >1800 LYs. Conclusions.Efforts to increase early living-donor RTx could potentially substantially increase LE for patients starting RRT, especially in younger patients.

Cost-effectiveness of screening for abdominal aortic aneurysm in the Netherlands and Norway (Article)

2011-11-01T00:00:00Z

Background: The aim of this study was to determine the cost-effectiveness of ultrasound screening for abdominal aortic aneurysm (AAA) in men aged 65 years, for both the Netherlands and Norway. Methods: A Markov model was developed to simulate life expectancy, quality-adjusted life-years, net health benefits, lifetime costs and incremental cost-effectiveness ratios for both screening and no screening for AAA. The best available evidence was retrieved from the literature and combined with primary data from the two countries separately, and analysed from a national perspective. A threshold willingness-to-pay (WTP) of €20 000 and €62 500 was used for data from the Netherlands and Norway respectively. Results: The additional costs of the screening strategy compared with no screening were €421 (95 per cent confidence interval 33 to 806) per person in the Netherlands, and the additional life-years were 0·097 (-0·180 to 0·365), representing €4340 per life-year. For Norway, the values were €562 (59 to 1078), 0·057 (-0·135 to 0·253) life-years and €9860 per life-year respectively. In Norway the results were sensitive to a decrease in the prevalence of AAA in 65-year-old men to 1 per cent, or lower. Probabilistic sensitivity analyses indicated that AAA screening has a 70 per cent probability of being cost-effective in the Netherlands with a WTP threshold of €20 000, and 70 per cent in Norway with a threshold of €62 500. Conclusion: Using this model, screening for AAA in 65-year-old men would be highly cost-effective in both the Netherlands and Norway. Copyright

Stable angina pectoris: Head-to-head comparison of prognostic value of cardiac CT and exercise testing (Article)

2011-11-01T00:00:00Z

Purpose: To determine and compare the prognostic value of cardiac computed tomographic (CT) angiography, coronary calcium scoring, and exercise electrocardiography (ECG) in patients with chest pain who are suspected of having coronary artery disease (CAD). Materials and Methods: This study complied with the Declaration of Helsinki, and the local ethics committee approved the study. Patients (n = 471) without known CAD underwent exercise ECG and dual-source CT at a rapid assessment outpatient chest pain clinic. Coronary calcification and the presence of 50% or greater coronary stenosis (in one or more vessels) were assessed with CT. Exercise ECG results were classified as normal, ischemic, or nondiagnostic. The primary outcome was a major adverse cardiac event (MACE), defined as cardiac death, nonfatal myocardial infarction, or unstable angina requiring hospitalization and revascularization beyond 6 months. Univariable and multivariable Cox regression analysis was used to determine the prognostic values, while clinical impact was assessed with the net reclassification improvement metric. Results: Follow-up was completed for 424 (90%) patients;the mean duration of follow-up was 2.6 years. A total of 44 MACEs occurred in 30 patients. Four of the MACEs were cardiac deaths and six were nonfatal myocardial infarctions. The presence of coronary calcification (hazard ratio [HR], 8.22 [95% confidence interval {CI}: 1.96, 34.51]), obstructive CAD (HR, 6.22 [95% CI: 2.77, 13.99]), and nondiagnostic stress test results (HR, 3.00 [95% CI: 1.26, 7.14]) were univariable predictors of MACEs. In the multivariable model, CT angiography findings (HR, 5.0 [95% CI: 1.7, 14.5]) and nondiagnostic exercise ECG results (HR, 2.9 [95% CI: 1.2, 7.0]) remained independent predictors of MACEs. CT angiography findings showed incremental value beyond clinical predictors and stress testing (global χ2, 37.7 vs 13.7; P<.001), whereas coronary calcium scores did not have further incremental value (global χ2, 38.2 vs 37.7; P = .40). Conclusion: CT angiography findings are a strong predictor of future adverse events, showing incremental value over clinical predictors, stress testing, and coronary calcium scores.

Prediction of intracranial findings on CT-scans by alternative modelling techniques (Article)

2011-10-27T00:00:00Z

Background: Prediction rules for intracranial traumatic findings in patients with minor head injury are designed to reduce the use of computed tomography (CT) without missing patients at risk for complications. This study investigates whether alternative modelling techniques might improve the applicability and simplicity of such prediction rules. Methods. We included 3181 patients with minor head injury who had received CT scans between February 2002 and August 2004. Of these patients 243 (7.6%) had intracranial traumatic findings and 17 (0.5%) underwent neurosurgical intervention. We analyzed sensitivity, specificity and area under the ROC curve (AUC-value) to compare the performance of various modelling techniques by 10 × 10 cross-validation. The techniques included logistic regression, Bayes network, Chi-squared Automatic Interaction Detection (CHAID), neural net, support vector machines, Classification And Regression Trees (CART) and "decision list" models. Results: The cross-validated performance was best for the logistic regression model (AUC 0.78), followed by the Bayes network model and the neural net model (both AUC 0.74). The other models performed poorly (AUC < 0.70). The advantage of the Bayes network model was that it provided a graphical representation of the relationships between the predictors and the outcome. Conclusions: No alternative modelling technique outperformed the logistic regression model. However, the Bayes network model had a presentation format which provided more detailed insights into the structure of the prediction problem. The search for methods with good predictive performance and an attractive presentation format should continue.

Comparative effectiveness and cost-effectiveness of computed tomography screening for coronary artery calcium in asymptomatic individuals (Article)

2011-10-11T00:00:00Z

Objectives: The aim of this study was to assess the (cost-) effectiveness of screening asymptomatic individuals at intermediate risk of coronary heart disease (CHD) for coronary artery calcium with computed tomography (CT). Background: Coronary artery calcium on CT improves prediction of CHD. Methods: A Markov model was developed on the basis of the Rotterdam Study. Four strategies were evaluated: 1) current practice; 2) current prevention guidelines for cardiovascular disease; 3) CT screening for coronary calcium; and 4) statin therapy for all individuals. Asymptomatic individuals at intermediate risk of CHD were simulated over their remaining lifetime. Quality-adjusted life years (QALYs), costs, and incremental cost-effectiveness ratios were calculated. Results: In men, CT screening was more effective and more costly than the other 3 strategies (CT vs. current practice: +0.13 QALY [95% confidence interval (CI): 0.01 to 0.26], +$4,676 [95% CI: $3,126 to $6,339]; CT vs. statin therapy: +0.04 QALY [95% CI: -0.02 to 0.13], +$1,951 [95% CI: $1,170 to $2,754]; and CT vs. current guidelines: +0.02 QALY [95% CI: -0.04 to 0.09], +$44 [95% CI: -$441 to $486]). The incremental cost-effectiveness ratio of CT calcium screening was $48,800/QALY gained. In women, CT screening was more effective and more costly than current practice (+0.13 QALY [95% CI: 0.02 to 0.28], +$4,663 [95% CI: $3,120 to $6,277]) and statin therapy (+0.03 QALY [95% CI: -0.03 to 0.12], +$2,273 [95% CI: $1,475 to $3,109]). However, implementing current guidelines was more effective compared with CT screening (+0.02 QALY [95% CI: -0.03 to 0.07]), only a little more expensive (+$297 [95% CI: -$8 to $633]), and had a lower cost per additional QALY ($33,072/QALY vs. $35,869/QALY). Sensitivity analysis demonstrated robustness of results in women but considerable uncertainty in men. Conclusions: Screening for coronary artery calcium with CT in individuals at intermediate risk of CHD is probably cost-effective in men but is unlikely to be cost-effective in women.

Selection for early surgery in asymptomatic mitral regurgitation: A Markov model (Article)

2011-10-03T00:00:00Z

Background: Current guidelines propose mitral valve repair in asymptomatic chronic mitral regurgitation (MR) when the likelihood of repair is 90% or more. As this figure is not evidence-based, we sought whether the results of a decision-analytic model could facilitate the selection between early surgery (ES) and watchful waiting (WW) based on current guidelines. Methods: A Markov model was developed to reflect the anticipated health states in MR (pre-operative, post-operative, post-complication and death). Risks and transitions were informed by the literature. Implications of the strategies for survival, quality-adjusted life years (QALYs), cost and cost-effectiveness were calculated from a US healthcare provider perspective. Results: In the reference case (90% repair), QALY with ES was superior to WW (11.2 [0.4-21.3] vs 10.7 [95%CI: 1.0-21.3]) at an incremental cost-effectiveness of $54,659 ($45,030-$64,288) per QALY. Sensitivity analyses of health benefit showed the main variables influencing outcome were repair rate, operative mortality and risks of heart failure and death with medical management. At the registry repair rate (50%), outcomes of ES were worse than WW, and threshold analysis showed that a repair rate of 84% was required for ES to be superior. High medical risk (yearly heart failure risk 5.6 ± 6.6% and mortality 2.5 ± 4%) was the most favorable scenario for surgery; ES was more effective when mortality in the WW group was > 3.5%/year. Conclusion: A Markov model might be used to guide the selection of asymptomatic patients for mitral repair, based on local variations in risk and complications as well as repair rate.

The impact of gender on prognosis after non-cardiac vascular surgery (Article)

2011-10-01T00:00:00Z

Objectives: The objective was to evaluate the impact of gender on long-term survival of patients who underwent non-cardiac vascular surgery. Design, Material and Methods: Our prospectively collected data contained information on 560 patients undergoing carotid endarterectomy (CEA), 923 elective abdominal aortic aneurysm repairs (AAA) and 1046 lower limb reconstructions (LLR). Patient characteristics and long-term mortality of women were compared to that of men. Kaplan-Meier (KM) survival curves were constructed for men and women, on which we superimposed age- and sex-matched KM survival curves of the general population. Cox proportional hazards regression was used to identify risk factors for mortality. Results: Men in the CEA group had statistically significant higher all-cause mortality, hazard rate ratio (HRR) 1.41 (95% CI 1.01-1.98) No differences in mortality between the genders were observed in the AAA and LLR groups. Overall, men had more co-morbidities but received more disease-specific medication compared to women. Women retained their higher life expectancy after CEA but lost it in the AAA and LLR groups. Conclusion: Women retain their higher life expectancy after CEA; however, after AAA repair and LLR, this advantage is lost. Both men and women received too little disease-specific medication, but women were worse off.

Burden of atherosclerosis improves the prediction of coronary heart disease but not cerebrovascular events: The Rotterdam Study (Article)

2011-08-01T00:00:00Z

AimsSince atherosclerosis is a systemic process, risk prediction would benefit from targeting multiple components of cardiovascular disease simultaneously. To this end, it is useful to examine the predictive value of non-invasive measures of atherosclerosis in various vascular beds for both coronary heart disease (CHD) and cerebrovascular disease.Methods and resultsBetween September 2003 and February 2006, 2153 asymptomatic participants (69.6 ± 6.6 years) from the Rotterdam Study underwent a multi-detector computed tomography scan. During a median follow-up of 3.5 years, 58 CHD events (myocardial infarction and CHD death) and 52 cerebrovascular events (TIA and stroke) occurred. Participants were classified into low (<5), intermediate (510), and high (>10) 5-year risk categories based on a refitted Framingham risk model. The model was extended by coronary, aortic arch, or carotid calcium and reclassification percentages were calculated. For the outcome CHD, the C-statistic improved from 0.693 for the Framingham refitted model to 0.743, 0.740, and 0.749 by addition of coronary, aortic arch, and carotid calcium, respectively. Reclassification was most substantial in the intermediate risk group where addition of coronary calcium reclassified 56 of persons [net reclassification improvement (NRI): 15; P < 0.01)]. Adding aortic arch calcium led to a reclassification of 32 of persons (NRI: 8; P 0.01) and adding carotid calcium reclassified 51 (NRI: 9; P 0.02). In contrast, calcification in any of the three vascular beds did not improve cerebrovascular risk prediction.ConclusionCoronary, aortic arch, and carotid artery calcification significantly improved risk prediction of CHD but not of cerebrovascular events.

Predictive factors for new onset or progression of knee osteoarthritis one year after trauma: MRI follow-up in general practice (Article)

2011-07-01T00:00:00Z

Objective: To prospectively evaluate prognostic factors for new onset or progression of degenerative change on follow-up MRI one year after knee trauma and the association with clinical outcome. Methods: Within a prospective observational cohort study in general practice, we studied a subgroup of 117 patients with acute knee trauma (mean age 41 years, 43% women). Degenerative change was scored on MRI at baseline and after one year follow-up. Multivariate logistic regression analysis was performed to evaluate prognostic factors for new onset or progressive degenerative change on follow-up MRI. Association between new or progressive degeneration and clinical outcome after one year was assessed. Results: On follow-up MRI 15% of patients with pre-existing knee osteoarthritis showed progression and 26% of patients demonstrated new degenerative change. The only statistically significant prognostic variable in the multivariate analysis was bone marrow oedema on initial MRI (OR 5.29 (95% CI 1.64-17.1), p∈=∈0.005). A significant association between new or progressive degenerative change and clinical outcome was found (p∈=∈0.003). Conclusion: Bone marrow oedema on MRI for acute knee injury is strongly predictive of new onset or progression of degenerative change of the femorotibial joint on follow-up MRI one year after trauma, which is reflected in clinical outcome.

Long-term effects of structured home-based exercise program on functional capacity and quality of life in patients with intermittent claudication (Article)

2011-07-01T00:00:00Z

Fakhry F, Spronk S, de Ridder M, den Hoed PT, Hunink MGM. Long-term effects of structured home-based exercise program on functional capacity and quality of life in patients with intermittent claudication. Objectives: To evaluate effects of a structured home-based exercise program on functional capacity and quality of life (QoL) in patients with intermittent claudication (IC) after 1-year follow-up, and to compare these results with those from a concurrent control group who received supervised exercise training (SET). Design: Comparative longitudinal cohort study. Setting: Referral center. Participants: Patients (N=142) with IC. Interventions: Structured home-based exercise training or SET. Main Outcome Measures: The maximum (pain-free) walking distance and the ankle-brachial index (ABI) (at rest and postexercise) were measured at baseline and after 6 and 12 months' follow-up. Additionally, QoL was evaluated using a self-administered questionnaire consisting of the Euroqol-5D (scale 01), rating scale (scale 0100), Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36; scale 0100), and the Vascular Quality of Life Questionnaire (VascuQol; scale 17). Comparison of the groups was performed with adjustment for the nonrandomized setting using propensity scoring. Results: One hundred forty-two patients with IC started the structured home-based exercise program, of whom 95 (67%) completed 12 months' follow-up. The mean relative improvement compared with baseline was statistically significant after 12 months' follow-up for the maximum and pain-free walking distance (342%, 95% confidence interval [CI], 169516; P<.01 and 338%, 95% CI, 42635; P=.03, respectively) and for the ABI postexercise (mean change, .06; 95% CI, .01.10; P=.02). For the QoL outcomes, the improvement compared with baseline was statistically significant after 12 months for the VascuQol (mean change, .42; 95% CI, .20.65; P<.01) and for the SF-36 physical functioning (mean change, 5.17; 95% CI, .779.56; P=.02). Compared with the structured home-based exercise program, patients in the control group showed significantly better results in the mean relative improvement of maximum and pain-free walking distance and change in the ABI at rest after 12 months' follow-up. Conclusions: Structured home-based exercise training is effective in improving both functional capacity and QoL in patients with IC and may be considered as a feasible and valuable alternative toSET, since supervised exercise programs are not often available.

The combined analysis of uncertainty and patient heterogeneity in medical decision models (Article)

2011-07-01T00:00:00Z

The analysis of both patient heterogeneity and parameter uncertainty in decision models is increasingly recommended. In addition, the complexity of current medical decision models commonly requires simulating individual subjects, which introduces stochastic uncertainty. The combined analysis of uncertainty and heterogeneity often involves complex nested Monte Carlo simulations to obtain the model outcomes of interest. In this article, the authors distinguish eight model types, each dealing with a different combination of patient heterogeneity, parameter uncertainty, and stochastic uncertainty. The analyses that are required to obtain the model outcomes are expressed in equations, explained in stepwise algorithms, and demonstrated in examples. Patient heterogeneity is represented by frequency distributions and analyzed with Monte Carlo simulation. Parameter uncertainty is represented by probability distributions and analyzed with 2nd-order Monte Carlo simulation (aka probabilistic sensitivity analysis). Stochastic uncertainty is analyzed with 1st-order Monte Carlo simulation (i.e., trials or random walks). This article can be used as a reference for analyzing complex models with more than one type of uncertainty and patient heterogeneity.

Prognostic value of cardiac computed tomography angiography (Article)

2011-06-21T00:00:00Z

Is positive affect associated with survival? a population-based study of elderly persons (Article)

2011-06-06T00:00:00Z

Study results on the association of positive affect with survival are conflicting. This disagreement potentially arises from poor control for health or negative affect and for the various age groups studied. The authors examined if positive affect predicts survival; whether this association is preserved after controlling for negative affect, socioeconomic status, lifestyle, and health; and whether this association varies with age. The study is set within the population-based Rotterdam Study (1997-2007) and included 4,411 participants aged 61 years or older, followed for on average 7.19 (standard deviation = 2.20) years. Positive affect was not consistently associated with survival across all ages. A significant interaction of positive affect with age on survival (P = 0.02) was found. Subsequent age stratification revealed that positive affect independently predicted survival in elderly persons aged <80 years (per affect score, hazard ratio = 0.96, 95% confidence interval: 0.93, 0.99) but not in those aged ≥80 years in fully adjusted models (hazard ratio = 1.00, 95% confidence interval: 0.96, 1.04). In the oldest old, the association was partly explained by differences in baseline health. In conclusion, the results suggest that there may be an association of positive affect with survival in the younger and middle old but not in the oldest old in whom perception of positive affect is more likely to be determined by health.

A clinical prediction rule for the diagnosis of coronary artery disease: Validation, updating, and extension (Article)

2011-06-01T00:00:00Z

AimsThe aim was to validate, update, and extend the DiamondForrester model for estimating the probability of obstructive coronary artery disease (CAD) in a contemporary cohort. Methods and resultsProspectively collected data from 14 hospitals on patients with chest pain without a history of CAD and referred for conventional coronary angiography (CCA) were used. Primary outcome was obstructive CAD, defined as <50 stenosis in one or more vessels on CCA. The validity of the DiamondForrester model was assessed using calibration plots, calibration-in-the-large, and recalibration in logistic regression. The model was subsequently updated and extended by revising the predictive value of age, sex, and type of chest pain. Diagnostic performance was assessed by calculating the area under the receiver operating characteristic curve (c-statistic) and reclassification was determined. We included 2260 patients, of whom 1319 had obstructive CAD on CCA. Validation demonstrated an overestimation of the CAD probability, especially in women. The updated and extended models demonstrated a c-statistic of 0.79 (95 CI 0.770.81) and 0.82 (95 CI 0.800.84), respectively. Sixteen per cent of men and 64 of women were correctly reclassified. The predicted probability of obstructive CAD ranged from 10 for 50-year-old females with non-specific chest pain to 91 for 80-year-old males with typical chest pain. Predictions varied across hospitals due to differences in disease prevalence. Conclusion Our results suggest that the DiamondForrester model overestimates the probability of CAD especially in women. We updated the predictive effects of age, sex, type of chest pain, and hospital setting which improved model performance and we extended it to include patients of 70 years and older.

Systematic review of guidelines on imaging of asymptomatic coronary artery disease (Article)

2011-04-05T00:00:00Z

Objectives: The purpose of this study was to critically appraise guidelines on imaging of asymptomatic coronary artery disease (CAD). Background: Various imaging tests exist to detect CAD in asymptomatic persons. Because randomized controlled trials are lacking, guidelines that address the use of CAD imaging tests may disagree. Methods: Guidelines in English published between January 1, 2003, and February 26, 2010, were retrieved using MEDLINE, Cumulative Index to Nursing and Allied Health Literature, the National Guideline Clearinghouse, the National Library for Health, the Canadian Medication Association Infobase, and the Guidelines International Network International Guideline Library. Guidelines developed by national and international medical societies from Western countries, containing recommendations on imaging of asymptomatic CAD were included. Rigor of development was scored by 2 independent reviewers using the Appraisal of Guidelines Research and Evaluation (AGREE) instrument. One reviewer performed full extraction of recommendations, which was checked by a second reviewer. Results: Of 2,415 titles identified, 14 guidelines met our inclusion criteria. Eleven of 14 guidelines reported relationship with industry. The AGREE scores varied across guidelines from 21% to 93%. Two guidelines considered cost effectiveness. Eight guidelines recommended against or found insufficient evidence for testing of asymptomatic CAD. The other 6 guidelines recommended imaging patients at intermediate or high CAD risk based on the Framingham risk score, and 5 considered computed tomography calcium scoring useful for this purpose. Conclusions: Guidelines on risk assessment by imaging of asymptomatic CAD contain conflicting recommendations. More research, including randomized controlled trials, evaluating the impact of imaging on clinical outcomes and costs is needed.

Systematic review of guidelines on abdominal aortic aneurysm screening (Article)

2011-02-15T00:00:00Z

Objectives: Usually, physicians base their practice on guidelines, but recommendations on the same topic may vary across guidelines. Given the uncertainties regarding abdominal aortic aneurysm (AAA) screening, physicians should be able to identify systematically and transparently developed recommendations. We performed a systematic review of AAA screening guidelines to assist physicians in their choice of recommendations. Methods: Guidelines in English published between January 1, 2003 and February 26, 2010 were retrieved using MEDLINE, CINAHL, the National Guideline Clearinghouse, the National Library for Health, the Canadian Medication Association Infobase, and the G-I-N International Guideline Library. Guidelines developed by national and international medical societies from Western countries, containing recommendations on AAA screening were included. Three reviewers independently assessed rigor of guideline development using the Appraisal of Guidelines Research and Evaluation (AGREE) instrument. Two independent reviewers performed extraction of recommendations. Results: Of 2415 titles identified, seven guidelines were included in this review. Three guidelines were less rigorously developed based on AGREE scores below 40%. All seven guidelines contained a recommendation for one-time screening of elderly men by ultrasonography to select AAAs ≥5.5 cm for elective surgical repair. Four guidelines, of which three were less rigorously developed, contained disparate recommendations on screening of women and middle-aged men at elevated risk. There was no agreement on the management of smaller AAAs. Conclusion: Consensus exists across guidelines on one-time screening of elderly men to detect and treat AAAs ≥5.5 cm. For other target groups and management of small AAAs, prediction models and cost-effectiveness analyses are needed to provide guidance.

Effectiveness of prophylactic implantation of cardioverter-defibrillators without cardiac resynchronization therapy in patients with ischaemic or non-ischaemic heart disease: A systematic review and meta-analysis (Article)

2010-11-01T00:00:00Z

Aims: Much controversy exists concerning the efficacy of primary prophylactic implantable cardioverter-defibrillators (ICDs) in patients with low ejection fraction due to coronary artery disease (CAD) or dilated cardiomyopathy (DCM). This is also related to the bias created by function improving interventions added to ICD therapy, e.g. resynchronization therapy. The aim was to investigate the efficacy of ICD-only therapy in primary prevention in patients with CAD or DCM.Methods and results: Public domain databases, MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials, were searched from 1980 to 2009 for randomized clinical trials of ICD vs. conventional therapy. Two investigators independently abstracted the data. Pooled estimates were calculated using both fixed-effects and random-effects models. Eight trials were included in the final analysis (5343 patients). Implantable cardioverter-defibrillators significantly reduced the arrhythmic mortality [relative risk (RR): 0.40; 95 confidence interval (CI): 0.27-0.67] and all-cause mortality (RR: 0.73; 95 CI: 0.64-0.82). Regardless of aetiology of heart disease, ICD benefit was similar for CAD (RR: 0.67; 95 CI: 0.51-0.88) vs. DCM (RR: 0.74; 95 CI: 0.59-0.93).Conclusions: The results of this meta-analysis provide strong evidence for the beneficial effect of ICD-only therapy on the survival of patients with ischaemic or non-ischaemic heart disease, with a left ventricular ejection fraction ≤35, if they are 40 days from myocardial infarction and ≥3 months from a coronary revascularization procedure.

Coronary calcium score improves classification of coronary heart disease risk in the elderly: The Rotterdam study (Article)

2010-10-19T00:00:00Z

Objectives The purpose of this study was to examine the effect of coronary artery calcium (CAC) on the classification of 10-year hard coronary heart disease (CHD) risk and to empirically derive cut-off values of the calcium score for a general population of elderly patients. Background Although CAC scoring has been found to improve CHD risk prediction, there are limited data on its impact in clinical practice. Methods The study comprised 2,028 asymptomatic participants (age 69.6 ± 6.2 years) from the Rotterdam Study. During a median follow-up of 9.2 years, 135 hard coronary events occurred. Persons were classified into low (<10%), intermediate (10% to 20%), and high (>20%) 10-year coronary risk categories based on a Framingham refitted risk model. In a second step, the model was extended by CAC, and reclassification percentages were calculated. Cutoff values of CAC for persons in the intermediate-risk category were empirically derived based on 10-year hard CHD risk. Results Reclassification by means of CAC scoring was most substantial in persons initially classified as intermediate risk. In this group, 52% of men and women were reclassified, all into more accurate risk categories. CAC values above 615 or below 50 Agatston units were found appropriate to reclassify persons into high or low risk, respectively. Conclusions In a general population of elderly patients at intermediate CHD risk, CAC scoring is a powerful method to reclassify persons into more appropriate risk categories. Empirically derived CAC cutoff values at which persons at intermediate risk reclassified to either high or low risk were 615 and 50 Agatston units, respectively.

Microstructural brain injury in post-concussion syndrome after minor head injury (Article)

2010-10-06T00:00:00Z

Introduction: After minor head injury (MHI), post-concussive symptoms commonly occur. The purpose of this study was to correlate the severity of post-concussive symptoms in MHI patients with MRI measures of microstructural brain injury, namely mean diffusivity (MD) and fractional anisotropy (FA), as well as the presence of microhaemorrhages. Methods: Twenty MHI patients and 12 healthy controls were scanned at 3 T using diffusion tensor imaging (DTI) and high-resolution gradient recalled echo (HRGRE) T2*-weighted sequences. One patient was excluded from the analysis because of bilateral subdural haematomas. DTI data were preprocessed using Tract Based Spatial Statistics. The resulting MD and FA images were correlated with the severity of post-concussive symptoms evaluated with the Rivermead Postconcussion Symptoms Questionnaire. The number and location of microhaemorrhages were assessed on the HRGRE T2*-weighted images. Results: Comparing patients with controls, there were no differences in MD. FA was decreased in the right temporal subcortical white matter. MD was increased in association with the severity of post-concussive symptoms in the inferior fronto-occipital fasciculus (IFO), the inferior longitudinal fasciculus and the superior longitudinal fasciculus. FA was reduced in association with the severity of post-concussive symptoms in the uncinate fasciculus, the IFO, the internal capsule and the corpus callosum, as well as in the parietal and frontal subcortical white matter. Microhaemorrhages were observed in one patient only. Conclusions: The severity of post-concussive symptoms after MHI was significantly correlated with a reduction of white matter integrity, providing evidence of microstructural brain injury as a neuropathological substrate of the post-concussion syndrome.

Carotid, aortic arch and coronary calcification are related to history of stroke: The Rotterdam Study (Article)

2010-10-01T00:00:00Z

Objective: Multidetector computed tomography (MDCT), which has been mainly used to study coronary atherosclerosis, also enables non-invasive measurement of carotid and aortic atherosclerosis and might be suitable for screening in the general population. The aim of this study was to investigate the associations of carotid artery, aortic arch and coronary artery calcification as assessed by MDCT, with presence of stroke. Methods: The study was embedded in the population-based Rotterdam Study and comprises 2521 persons (mean age 69.7 ± 6.8 years, 48% males) that underwent an MDCT scan. History of stroke was reported by 96 persons. We used multivariable logistic regression to investigate the associations of calcification in the carotid arteries, aortic arch, and coronary arteries with presence of stroke. Results: We found strong and graded associations of prevalent stroke with carotid artery (OR quartile 4 versus 1 (95% CI): 5.0 (2.2-11.0)), aortic arch (3.3 (1.5-7.4)) and coronary artery calcification (3.1 (1.3-7.3)), independent of cardiovascular risk factors. Only the association of carotid artery calcification with presence of stroke was independent of calcification in the other two vessel beds. Conclusion: In this population-based study, we found a strong and graded association of prevalent stroke with carotid artery, aortic arch and coronary artery calcification, independent of cardiovascular risk factors. After additional adjustment for calcification in the other vessel beds, prevalent stroke was still significantly related to carotid calcification, but no longer to aortic arch or coronary calcification.

Incremental value of the CT coronary calcium score for the prediction of coronary artery disease (Article)

2010-10-01T00:00:00Z

Objectives:: To validate published prediction models for the presence of obstructive coronary artery disease (CAD) in patients with new onset stable typical or atypical angina pectoris and to assess the incremental value of the CT coronary calcium score (CTCS). Methods:: We searched the literature for clinical prediction rules for the diagnosis of obstructive CAD, defined as≥50% stenosis in at least one vessel on conventional coronary angiography. Significant variables were re-analysed in our dataset of 254 patients with logistic regression. CTCS was subsequently included in the models. The area under the receiver operating characteristic curve (AUC) was calculated to assess diagnostic performance. Results:: Re-analysing the variables used by Diamond & Forrester yielded an AUC of 0.798, which increased to 0.890 by adding CTCS. For Pryor, Morise 1994, Morise 1997 and Shaw the AUC increased from 0.838 to 0.901, 0.831 to 0.899, 0.840 to 0.898 and 0.833 to 0.899. CTCS significantly improved model performance in each model. Conclusions:: Validation demonstrated good diagnostic performance across all models. CTCS improves the prediction of the presence of obstructive CAD, independent of clinical predictors, and should be considered in its diagnostic work-up. © 2010 The Author(s).

Suspected carotid artery stenosis: Cost-effectiveness of CT angiography in work-up of patients with recent TIA or minor ischemic stroke (Article)

2010-08-01T00:00:00Z

Purpose: To assess the effectiveness and cost-effectiveness of state-of-the-art noninvasive diagnostic imaging strategies in patients with a transient ischemic attack (TIA) or minor stroke who are suspected of having carotid artery stenosis (CAS). Materials and Methods: All prospectively evaluated patients provided informed consent, and the local ethics committee approved this study. Diagnostic performance, treatment, long-term events, quality of life, and costs resulting from strategies employing duplex ultrasonography (US), computed tomographic (CT) angiography, contrast material-enhanced magnetic resonance (MR) angiography, and combinations of these modalities were modeled in a decision tree and Markov model. Data sources included a prospective diagnostic cohort study, a meta-analysis, and a review of the literature. Outcomes were costs, quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios, and net health benefits (QALY-equivalents), with a willingness-to-pay threshold of €50 000 per QALY and a societal perspective. The strategy with the highest net health benefit was considered the most cost effective. Extensive one-way, two-way, and probabilistic sensitivity analyses to explore the effect of varying parameter values were performed. The reference case analysis assumed that patients underwent surgery 2-4 weeks after the first symptoms, and the effect of earlier intervention was explored. Results: The reference case analysis showed that duplex US combined with CT angiography and surgery for 70%-99% stenoses was the most cost-effective strategy, with a net health benefit of 13.587 and 15.542 QALY-equivalents in men and women, respectively. In men, the CT angiography strategy with a 70%-99% cutoff yielded slightly more QALYs, at an incremental cost of €71 419 per QALY, compared with duplex US combined with CT angiography. In patients with a high-risk profile, in patients with a high prior probability of disease, and when patients could be treated within 2 weeks after the first symptoms, the CT angiography strategy with surgery for 50%-99% stenoses was the most cost-effective strategy. Conclusion: In diagnosing CAS, duplex US should be the initial test, and, if its results are positive, CT angiography should be performed; patients with 70%-99% stenoses should then undergo carotid endarterectomy. In patients with a high-risk profile, a high probability of CAS, or who can undergo surgery without delay, immediate CT angiography and surgery for 50%-99% stenoses is indicated.

Improvement of risk prediction by genomic profiling: Reclassification measures versus the area under the receiver operating characteristic curve (Article)

2010-08-01T00:00:00Z

Reclassification is observed even when there is no or minimal improvement in the area under the receiver operating characteristic curve (AUC), and it is unclear whether it indicates improved clinical utility. The authors investigated total reclassification, net reclassification improvement, and integrated discrimination improvement for different ΔAUC using empirical and simulated data. Empirical analyses compared prediction of type 2 diabetes risk based on age, sex, and body mass index with prediction updated with 18 established genetic risk factors. Simulated data were used to investigate measures of reclassification against ΔAUCs of 0.005, 0.05, and 0.10. Total reclassification and net reclassification improvement were calculated for all possible cutoff values. The AUC of type 2 diabetes risk prediction improved from 0.63 to 0.66 when 18 polymorphisms were added, whereas total reclassification ranged from 0% to 22.5% depending on the cutoff value chosen. In the simulation study, total reclassification, net reclassification improvement, and integrated discrimination improvement increased with higher ΔAUC. When ΔAUC was low (0.005), net reclassification improvement values were close to zero, integrated discrimination improvement was 0.08% (P > 0.05), but total reclassification ranged from 0 to 6.7%. Reclassification increases with increasing AUC but predominantly varies with the cutoff values chosen. Reclassification observed in the absence of AUC increase is unlikely to improve clinical utility.

Propensity scores in the presence of effect modification: A case study using the comparison of mortality on hemodialysis versus peritoneal dialysis (Article)

2010-05-13T00:00:00Z

Purpose. To control for confounding bias from non-random treatment assignment in observational data, both traditional multivariable models and more recently propensity score approaches have been applied. Our aim was to compare a propensity score-stratified model with a traditional multivariable-adjusted model, specifically in estimating survival of hemodialysis (HD) versus peritoneal dialysis (PD) patients. Methods. Using the Dutch End-Stage Renal Disease Registry, we constructed a propensity score, predicting PD assignment from age, gender, primary renal disease, center of dialysis, and year of first renal replacement therapy. We developed two Cox proportional hazards regression models to estimate survival on PD relative to HD, a propensity score-stratified model stratifying on the propensity score and a multivariable-adjusted model, and tested several interaction terms in both models. Results. The propensity score performed well: it showed a reasonable fit, had a good c-statistic, calibrated well and balanced the covariates. The main-effects multivariable-adjusted model and the propensity score-stratified univariable Cox model resulted in similar relative mortality risk estimates of PD compared with HD (0.99 and 0.97, respectively) with fewer significant covariates in the propensity model. After introducing the missing interaction variables for effect modification in both models, the mortality risk estimates for both main effects and interactions remained comparable, but the propensity score model had nearly as many covariates because of the additional interaction variables. Conclusion. Although the propensity score performed well, it did not alter the treatment effect in the outcome model and lost its advantage of parsimony in the presence of effect modification.

Cost-effectiveness of breech version by acupuncture-type interventions on BL 67, including moxibustion, for women with a breech foetus at 33 weeks gestation: A modelling approach (Article)

2010-04-01T00:00:00Z

Objectives: To assess, using a modelling approach, the effectiveness and costs of breech version with acupuncture-type interventions on BL67 (BVA-T), including moxibustion, compared to expectant management for women with a foetal breech presentation at 33 weeks gestation. Design: A decision tree was developed to predict the number of caesarean sections prevented by BVA-T compared to expectant management to rectify breech presentation. The model accounted for external cephalic versions (ECV), treatment compliance, and costs for 10,000 simulated breech presentations at 33 weeks gestational age. Event rates were taken from Dutch population data and the international literature, and the relative effectiveness of BVA-T was based on a specific meta-analysis. Sensitivity analyses were conducted to evaluate the robustness of the results. Main outcome measures: We calculated percentages of breech presentations at term, caesarean sections, and costs from the third-party payer perspective. Odds ratios (OR) and cost differences of BVA-T versus expectant management were calculated. (Probabilistic) sensitivity analysis and expected value of perfect information analysis were performed. Results: The simulated outcomes demonstrated 32% breech presentations after BVA-T versus 53% with expectant management (OR 0.61, 95% CI 0.43, 0.83). The percentage caesarean section was 37% after BVA-T versus 50% with expectant management (OR 0.73, 95% CI 0.59, 0.88). The mean cost-savings per woman was €451 (95% CI €109, €775; p=0.005) using Moxibustion. Sensitivity analysis showed that if 16% or more of women offered moxibustion complied, it was more effective and less costly than expectant management. To prevent one caesarean section, 7 women had to use BVA-T. The expected value of perfect information from further research was €0.32 per woman. Conclusions: The results suggest that offering BVA-T to women with a breech foetus at 33 weeks gestation reduces the number of breech presentations at term, thus reducing the number of caesarean sections, and is cost-effective compared to expectant management, including external cephalic version.

Value of information analyses of economic randomized controlled trials: The treatment of intermittent claudication (Article)

2010-03-01T00:00:00Z

Objective: The aim of this study is to design the optimal study comparing endovascular revascularization and supervised exercise training for patients with intermittent claudication and to demonstrate value of information (VOI) analysis of patient-level data from an economic randomized controlled trial to guide future research. Methods: We applied a net benefit framework to patient-level data on costs and quality-of-life of a previous randomized controlled trial. VOI analyses were performed using Monte Carlo simulation. We estimated the total expected value of perfect information (total EVPI), the total expected value of sample information (total EVSI), the partial expected value of perfect information (partial EVPI), and the partial expected value of sample information (partial EVSI). These VOI analyses identified the key parameters and the optimal sample size of future study designs. Sensitivity analyses were performed to explore the robustness of our assumptions about the population to benefit, the willingness-to-pay threshold, and the study costs. The VOI analyses are demonstrated in statistical software (R) and a spreadsheet (Excel) allowing other investigators to apply VOI analysis to their patient-level data. Results: The optimal study design for the treatment of intermittent claudication involves a randomized controlled trial collecting data on the quality-adjusted life expectancy and additional admission costs for 525 patients per treatment arm. The optimal sample size remained between 400 and 600 patients for a willingness-to-pay threshold between €30,000 and €100,000/quality-adjusted life-years, for even extreme assumptions about the study costs, and for a range of 3 to 7 years that future patients will benefit from the results of the proposed study. Conclusions: 1) The optimal study for patients with intermittent claudication collects data on two key parameters for 525 patients per trial arm; and 2) we have shown that value of information analysis provides an explicit framework to determine the optimal sample size and identify key parameters for the design of future clinical trials.

Uncertainty and patient heterogeneity in medical decision models (Article)

2010-03-01T00:00:00Z

Parameter uncertainty, patient heterogeneity, and stochastic uncertainty of outcomes are increasingly important concepts in medical decision models. The purpose of this study is to demonstrate the various methods to analyze uncertainty and patient heterogeneity in a decision model. The authors distinguish various purposes of medical decision modeling, serving various stakeholders. Differences and analogies between the analyses are pointed out, as well as practical issues. The analyses are demonstrated with an example comparing imaging tests for patients with chest pain. For complicated analyses step-by-step algorithms are provided. The focus is on Monte Carlo simulation and value of information analysis. Increasing model complexity is a major challenge for probabilistic sensitivity analysis and value of information analysis. The authors discuss nested analyses that are required in patient-level models, and in nonlinear models for analyses of partial value of information analysis.

Minor head injury: CT-based strategies for management--a cost-effectiveness analysis (Article)

2010-02-01T00:00:00Z

Purpose: To compare the cost-effectiveness of using selective computed tomographic (CT) strategies with that of performing CT in all patients with minor head injury (MHI). Materials and methods: The internal review board approved the study; written informed consent was obtained from all interviewed patients. Five strategies were evaluated, with CT performed in all patients with MHI; selectively according to the New Orleans criteria (NOC), Canadian CT head rule (CCHR), or CT in head injury patients (CHIP) rule; or in no patients. A decision tree was used to analyze short-term costs and effectiveness, and a Markov model was used to analyze long-term costs and effectiveness. n-Way and probabilistic sensitivity analyses and value-of-information (VOI) analysis were performed. Data from the multicenter CHIP Study involving 3181 patients with MHI were used. Outcome measures were first-year and lifetime costs, quality-adjusted life-years, and incremental cost-effectiveness ratios. Results: Study results showed that performing CT selectively according to the CCHR or the CHIP rule could lead to substantial U.S. cost savings ($120 million and $71 million, respectively), and the CCHR was the most cost-effective at reference-case analysis. When the prediction rule had lower than 97% sensitivity for the identification of patients who required neurosurgery, performing CT in all patients was cost-effective. The CHIP rule was most likely to be cost-effective. At VOI analysis, the expected value of perfect information was $7 billion, mainly because of uncertainty about long-term functional outcomes. Conclusion: Selecting patients with MHI for CT renders cost savings and may be cost-effective, provided the sensitivity for the identification of patients who require neurosurgery is extremely high. Uncertainty regarding long-term functional outcomes after MHI justifies the routine use of CT in all patients with these injuries.

Value-of-information analysis to guide future research in the management of the colorectal malignant polyp (Article)

2010-02-01T00:00:00Z

Purpose: The efficacy of surgery in the postendoscopic management of low-risk malignant polyps is unclear. Although interobserver variability in the histological diagnosis was shown, its importance is unknown. The purpose of this study was to guide future research on the optimal strategy for low-risk polyps with the use of valueof- information analysis. Methods: A decision-analysis model was constructed comparing the strategies of referring or not referring (waiting) to surgery patients with low-risk polyps. Probabilistic sensitivity analysis was performed to explore the effect of uncertainty about the input parameters. Value-of-information analysis was used to estimate the expected benefit of future research that would eliminate the decision uncertainty. Results: The number of postendoscopic surgeries to prevent 1 cancer-related death was 208. The incremental cost-effectiveness ratio of surgery vs waiting strategy was $215,291/life-year gained, surgery being a suboptimal choice in the reference case analysis. Probabilistic sensitivity analysis demonstrated that surgery was the optimal choice in 61% of the simulated scenarios. Most of the decision uncertainty was related with the combination of histological inaccuracy, prevalence of residual disease, and surgical mortality. The expected societal monetary benefit of further research from the perspective of the United States was estimated to be $1 billion. Conclusions: The small benefit and the relatively high costs associated with surgery argue against surgical referral for low-risk malignant polyps; however, when a suboptimal histopathological accuracy was simulated, surgery appeared to be the most cost-effective option, prompting the need for further research.

Systematic review of guidelines on cardiovascular risk assessment: Which recommendations should clinicians follow for a cardiovascular health check? (Article)

2010-01-11T00:00:00Z

Objective: To appraise guidelines on cardiovascular risk assessment to guide selection of screening interventions for a health check. Data Sources: Guidelines in the English language published between January 1, 2003, and May 2, 2009, were retrieved using MEDLINE and CINAHL. This was supplemented by searching the National Guideline Clearinghouse, National Library for Health, Canadian Medical Association Infobase, and G-I-N International Guideline Library. Study Selection: We included guidelines developed on behalf of professional organizations from Western countries, containing recommendations on cardiovascular risk assessment for the apparently healthy population. Titles and abstracts were assessed by 2 independent reviewers. Of 1984 titles identified, 27 guidelines met our criteria. Data Extraction: Rigor of guideline development was assessed by 2 independent reviewers. One reviewer extracted information on conflicts of interest and recommendations. Results: Sixteen of 27 guidelines reported conflicts of interest and 17 showed considerable rigor. These included recommendations on assessment of total cardiovascular risk (7 guidelines), dyslipidemia (2), hypertension (2), and dysglycemia (7). Recommendations on total cardiovascular risk and dyslipidemia included prediction models integrating multiple risk factors, whereas remaining recommendations were focused on single risk factors. No consensus was found on recommended target populations, treatment thresholds, and screening tests. Conclusions: Differences among the guidelines imply important variation in allocation of preventive interventions. To make informed decisions, physicians should use only the recommendations from rigorously developed guidelines.

MRI follow-up of conservatively treated meniscal knee lesions in general practice (Article)

2010-01-01T00:00:00Z

Objective: To evaluate meniscal status change on follow-up MRI after 1 year, prognostic factors and association with clinical outcome in patients with conservatively treated knee injury. Methods: We analysed 403 meniscal horns in 101 conservatively treated patients (59 male; mean age 40 years) in general practice who underwent initial knee MRI within 5 weeks of trauma. We performed ordinal logistic regression analysis to analyse prognostic factors for meniscal change on follow-up MRI after 1 year, and we assessed the association with clinical outcome. Results: On follow-up MRI 49 meniscal horns had deteriorated and 18 had improved. Age (odds ratio [OR] 1.3/decade), body weight (OR 1.2/10 kg), total anterior cruciate ligament (ACL) rupture on initial MRI (OR 2.4), location in the posterior horn of the medial meniscus (OR 3.0) and an initial meniscal lesion (OR 0.3) were statistically significant predictors of meniscal MRI appearance change after 1 year, which was not associated with clinical outcome. Conclusion: In conservatively treated patients, meniscal deterioration on follow-up MRI 1 year after trauma is predicted by higher age and body weight, initial total ACL rupture, and location in the medial posterior horn. Change in MRI appearance is not associated with clinical outcome.

Value-of-information analysis to guide future research in colorectal cancer screening (Article)

2009-12-01T00:00:00Z

Purpose: To identify the most useful areas for research in colorectal cancer (CRC) screening by using a value-of-information analysis. Materials and Methods: Cost-effectiveness of screening strategies, including colonoscopy, computed tomographic (CT) colonography, flexible sigmoidoscopy, and barium enema examination, were compared by using a Markov model. Monetary net benefit (NB), a measure of cost-effectiveness, was calculated by multiplying effect (life-years gained) by willingness to pay ($100 000 per life-year gained) and subtracting cost. A value-of-information analysis was used to estimate the expected benefit of future research that would eliminate the decision uncertainty. Results: In the reference-case analysis, colonoscopy was the optimal test with the highest NB ($1945 per subject invited for screening compared with $1862, $1717, and $1653 for CT colonography, flexible sigmoidoscopy, and barium enema examination, respectively). Results of probabilistic sensitivity analysis indicated that colonoscopy was the optimal choice in only 45% of the simulated scenarios, whereas CT colonography, flexible sigmoidoscopy, and barium enema examination were the optimal strategies in 23%, 16%, and 15% of the scenarios, respectively. Only two parameters were responsible for most of this uncertainty about the optimal test for CRC screening: the increase in adherence with less invasive tests and CRC natural history. The expected societal monetary benefit of further research in these areas was estimated to be more than $15 billion. Conclusion: Results of value-of-information analysis show that future research on the optimal test for CRC screening has a large societal impact. Priority should be given to research on the increase in adherence with screening by using less invasive tests and to better understanding of the natural history of CRC.

CT coronary angiography in patients suspected of having coronary artery disease: Decision making from various perspectives in the face of uncertainty (Article)

2009-12-01T00:00:00Z

Purpose: To determine the cost-effectiveness of computed tomographic (CT) coronary angiography as a triage test, performed prior to conventional coronary angiography, by using a Markov model. Materials and Methods: A Markov model was used to analyze the cost-effectiveness of CT coronary angiography performed as a triage test prior to conventional coronary angiography from the perspective of the patient, physician, hospital, health care system, and society by using recommendations from the United Kingdom, the United States, and the Netherlands for cost-effectiveness analyses. For CT coronary angiography, a range of sensitivities (79%-100%) and specificities (63%-94%) were used to help diagnose significant coronary artery disease (CAD). Optimization criteria (ie, outcomes considered) were: revised posttest probability of CAD, life-years, quality-adjusted life-years (QALYs), costs, and incremental cost-effectiveness ratios (ICERs). Extensive sensitivity analysis was performed. Results: For a prior probability of CAD of less than 40%, the probability of CAD after CT coronary angiography with negative results was less than 1%. The Markov model calculations from the patient/physician perspective suggest that CT coronary angiography maximizes life-years respectively in 60-year-old men and women at a prior probability of less than 38% and 24% and maximizes QALYs at a prior probability of less than 17% and 11%. From the hospital/health care perspective, CT coronary angiography helps reduce health care and direct nonhealth care-related costs (according to UK/U.S. recommendations), regardless of prior probability, and lowers all costs, including production losses (Netherlands recommendations) at a prior probability of less than 87%-92%. Analysis performed from a societal perspective by using a willingness-topay threshold level of €80 000/QALY suggests that CT coronary angiography is cost-effective when the prior probability is lower than 44% and 37% in men and women, respectively. Sensitivity analyses showed that results changed across the reported range of sensitivity of CT coronary angiography. Conclusion: The optimal diagnostic work-up depends on the optimization criterion, prior probability of CAD, and the diagnostic performance of CT coronary angiography.

Complex regional pain syndrome type 1 may be associated with menstrual cycle disorders: A case-control study (Article)

2009-10-01T00:00:00Z

Background: Complex regional pain syndrome type 1 (CRPS1) can develop after severe trauma or surgery in the limbs, and presents with chronic, changes in temperature, edema and dysfunction. Seventy-five percent of CRPS1 patients are female. While neurological and inflammatory components have been proposed, the etiology remains unclear. No consensus on optimal management of CRPS1 exists. In traditional Chinese medicine, menstrual disorders are related to the state of women's constitution and therefore identify their pain patterns. A classification by constitution might improve the pain management in CRPS1 patients. It is unknown whether associations exist between menstrual-cycle-conditions and CRPS1. Aim: To investigate whether a specified menstrual condition is associated with the risk of developing CRPS1. Methods: A population-based case-control study of CRPS1 was conducted among Dutch women aged 18-82; i.e. 34 women with CRPS1 and 147 controls. A standard questionnaire consisting of 59 menstrual-cycle-symptom-based questions was administered. From this questionnaire, 15 CRPS1-related questions (DRQ 15) were analyzed. We used multivariate logistic regression to obtain odds ratios and 95% confidence intervals (CI) for specified menstrual disorders adjusting for age, oral contraceptives, hysterectomy and age at menarche ≤12 and ≥17 years. Results: On the basis of the DRQ 15, women with CRPS1 were 5.3 (95%CI 2.1, 12.9) times more likely to have menstrual disorders than comparable controls. Conclusion: Our results suggest that selected menstrual conditions are associated with the risk of developing CRPS1.

Postconcussion syndrome after minor head injury: Brain activation of working memory and attention (Article)

2009-09-15T00:00:00Z

After minor head injury (MHI) postconcussive symptoms (PCS) such as memory and attention deficits frequently occur. It has been hypothesised that PCS are caused by microstructural damage to the brain due to shearing injury, which is not detectable with conventional imaging, and may be responsible for a functional deficit. The purpose of this study was to correlate functional magnetic resonance imaging brain activation of working memory and selective attention with PCS. 21 MHI patients and 12 healthy controls were scanned at 3T. Stimulation paradigms were the n-back and Counting Stroop tasks to engage working memory and selective attention, respectively. Functional data analysis consisted of random effects group analyses, correlating brain activation patterns with the severity of PCS as evaluated with the Rivermead postconcussion symptoms questionnaire. At minimal working memory load, activation was seen in patients with greater severity of PCS in the working memory network. With an increase of working memory load, increase of activation was more pronounced in patients with greater severity of PCS. At high and increased working memory load, activation associated with the severity of PCS was seen in the posterior parietal area, parahippocampal gyrus, and posterior cingulate gyrus. Activation related to selective attention processing was increased with greater severity of PCS. The increased activity in relation to working memory and attention, and the recruitment of brain areas outside the working memory network at high working memory load, may be considered a reflection of the brain's compensatory response to microstructural injury in patients with PCS.

Hepatocellular adenoma: Cost-effectiveness of different treatment strategies (Article)

2009-09-01T00:00:00Z

Purpose: To determine the effectiveness, costs, and cost-effectiveness of strategies for the management of hepatocellular adenoma (HA) in women who are otherwise healthy. Materials and Methods: A Markov model was developed to estimate the quality-adjusted life expectancy (in quality-adjusted life-years [QALYs]), lifetime costs (in 2007 U.S. dollars), and net health benefits (QALY equivalent) of surgery, transarterial embolization (TAE), radiofrequency ablation (RFA), and watchful waiting. Model parameters and their distributions were derived from the literature and the hospital database. Results: In patients with HA tumors suitable for RFA, RFA had the highest effectiveness (23.89 QALYs) and lowest costs ($2965). The treatment decision was sensitive to RFA-related mortality. In patients with tumors unsuitable for RFA, watchful waiting combined with TAE in cases of hemorrhage had the highest effectiveness (23.83 QALYs) and lowest costs ($8493). The treatment decision was sensitive to probability of tumor growth, probability of hemorrhage, and hemorrhage-related mortality. Conclusion: According to the model results, the most favorable treatment strategy for patients with small HAs was RFA. In patients with HA unsuitable for RFA, watchful waiting was the optimal strategy.

Cost-effectiveness analysis for surgeons (Article)

2009-06-01T00:00:00Z

Learning curve for coronary CT angiography: What constitutes sufficient training? (Article)

2009-05-01T00:00:00Z

Purpose: To prospectively evaluate the effect of experience with coronary computed tomographic (CT) angiography on the capability to detect coronary stenoses of 50% or more. Materials and Methods: The institutional review board approved the study protocol. All patients gave consent to undergo CT angiography before conventional coronary angiography after being informed of the additional radiation dose. They also consented to the use of their data for future research. Three radiologists and one cardiologist inexperienced with coronary CT angiography attended this institution's cardiac CT unit for a 1-year fellowship. Fellows were involved in the acquisition and reading of 12-15 coronary CT angiograms per week (about 600 per year). To assess the progression in diagnostic performance, fellows (readers) independently read 50 CT angiographic test cases in patients who also underwent conventional coronary angiography. Cases were repeatedly assigned in random order at baseline and at 4, 8, 26, and 52 weeks. The same cases were examined by two experts in consensus. Sensitivity, specificity, and diagnostic odds ratios (DORs) were calculated and compared with conventional coronary angiography as the reference standard. Results: Respective reader ranges for sensitivity, specificity, and DOR were 33%-72%, 70%-94%, and 3.8-8.1 at baseline; 43%-80%, 71%-88%, and 8.8-15.2 after 6 months; and 66%-75%, 87%-92%, and 14.7-25.8 after 1 year. For expert physicians, respective results were 95%, 93%, and 255.9. Between baseline and 6 months, readers 1-3 showed nonsignificantly improved sensitivities, while specificities remained similar. Reader 4 showed significantly improved specificity, while sensitivity remained similar; all readers nonsignificantly improved DORs. Between baseline and 1 year: readers 1 and 2 significantly improved sensitivity but not specificity; reader 4 significantly improved specificity but not sensitivity; readers 1, 2, and 4 improved DOR significantly; reader 3 nonsignificantly improved sensitivity, specificity, and DOR. Conclusion: Increasing experience with coronary CT angiography improved the diagnostic performance of inexperienced physicians. However, acquiring expertise in coronary CT angiography was slow and may take more than 1 year.

Invasive treatment of claudication is indicated for patients unable to adequately ambulate during cardiac rehabilitation (Article)

2009-05-01T00:00:00Z

Background: Cardiac rehabilitation (CR) is of proven benefit for patients with coronary artery disease. Patients who successfully complete CR have a statistically significant reduction in the risk of fatal myocardial infarction (MI) and all-cause mortality. Peripheral arterial disease (PAD) is common in patients with coronary artery disease. Objectives: We investigated whether PAD prevents the successful completion of CR and cardiac risk reduction and whether invasive treatment of claudicant patients who cannot walk sufficiently to successfully complete CR is indicated. Methods: The records of 230 consecutive CR patients were reviewed for attendance, target heart rate, and Walking Impairment Questionnaire (WIQ) values to compare PAD among successes and failures. Failure of CR was defined as inability to walk sufficiently to achieve target heart rate. Markov decision analysis using published data for endovascular and open intervention for claudication was used to compare outcomes of treatment strategies in which PAD is untreated (current standard), PAD is treated only if it interfered with CR, and treatment of PAD in all patients before initiating CR. Results: Of 230 patients, 126 had complete records for analysis. Ankle-brachial indices (ABIs) were documented for 39 patients. Overall, 40% of patients failed CR. Failure was significantly more common in patients with claudication (76%) than in those without (26%; odds ratio [OR], 8.9; 95% confidence interval [CI], 3.7-21.7; P < .001). The presence of PAD, determined by the WIQ walking distance score, was significantly higher in the failure group (34%) vs the success group (17%; OR, 2.5; 95% CI, 1.1-6.0; P = .03). The presence of PAD, determined by ABI, was higher in the failure group (39%) vs the success group (14%; OR, 3.8; 95% CI, 0.8-17.9; P = .08). Logistic regression analysis when CR failure was adjusted for age and gender was significantly associated with presence of PAD based on WIQ walking distance score (OR, 2.8; 95% CI 1.1-7.1; P = .03). A strategy of invasive therapy only if PAD interfered with the successful completion of CR would save an additional 54 lives per 10,000 patients compared with no intervention. Conclusions: PAD is a significant cause of CR failure, preventing patients from successfully completing the program and achieving a reduction in risk of fatal cardiac events. Invasive treatment of PAD in patients who fail CR is indicated, with an expected lifesaving outcome.

Minimally invasive autopsy: An alternative to conventional autopsy? (Article)

2009-03-01T00:00:00Z

Purpose: To determine the diagnostic performance of minimally invasive autopsy (MIA) for detection of causes of death and to investigate the feasibility of MIA as an alternative to conventional autopsy (CA) in the clinical setting. Materials and Methods: The institutional review board approved the MIA procedure and study, and informed consent was obtained for all deceased patients from relatives. Thirty deceased patients (19 men, 11 women;age range, 46-79 years), for whom family permission for CA on medical grounds had already been obtained, underwent additional evaluation with MIA prior to CA. MIA consisted of whole-body 16-section computed tomography (CT) and 1.5-T magnetic resonance (MR) imaging, followed by ultra-sonography-guided 12-guage needle biopsy of heart, both lungs, liver, both kidneys, and spleen. Percentage agreement between MIA and CA on cause of death was evaluated. Sensitivity and corresponding 95% confidence intervals (CIs) of MIA for detection of overall (major plus minor) findings, with CA as the reference standard, were calculated. Specificity was calculated for overall findings. Sensitivity analysis was performed to explore the effect of the clustered nature of the data. Results: In 23 patients (77%), MIA and CA were in agreement on the cause of death. Sensitivity of MIA for detection of overall findings and detection of major findings was 93% (95% CI: 90%, 96%) and 94% (95% CI: 87%, 97%), respectively. Specificity was 99% (95% CI: 98%, 99%) for detection of overall findings. MIA failed to demonstrate acute myocardial infarction as the cause of death in four patients. Sensitivity analysis indicated a negligible correlation between observations within each patient. CT was superior to MR for detection of pneumothorax and calcifications. MR was superior to CT for detection of brain abnormalities and pulmonary embolus. With biopsy only, detection of disease in 55 organs was possible, which included 27 major findings. Conclusion: MIA is a feasible procedure with high diagnostic performance for detection of common causes of death such as pneumonia and sepsis;MIA failed to demonstrate cardiac diseases, such as acute myocardial infarction and endocarditis, as underlying cause of death.

Costs and effectiveness of a brief MRI examination of patients with acute knee injury (Article)

2009-02-01T00:00:00Z

The aim of this study was to assess the costs and effectiveness of selective short magnetic resonance imaging (MRI) in patients with acute knee injury. A model was developed to evaluate the selective use of MRI in patients with acute knee injury and no fracture on radiography based on the results of a trial in which 208 patients were randomized between radiography only and radiography plus MRI. We analyzed medical (diagnostic and therapeutic) costs, quality of life, duration of diagnostic workup, number of additional diagnostic examinations, time absent from work, and time to convalescence during a 6-month follow-up period. Quality of life was lowest (EuroQol at 6 weeks 0.61 (95% CI 0.54–0.67)); duration of diagnostic workup, absence from work, and time to convalescence were longest; and the number of diagnostic examinations was largest with radiography only. These outcomes were more favorable for both MRI strategies (EuroQol at 6 weeks 0.72 (95% CI 0.67–0.77) for both). Mean total costs were 2,593 euros (95% CI 1,815–3,372) with radiography only, 2,116 euros (95% CI 1,488–2,743) with radiography plus MRI, and 1,973 euros (95% CI 1,401–2,543) with selective MRI. The results suggest that selective use of a short MRI examination saves costs and potentially increases effectiveness in patients with acute knee injury without a fracture on radiography.

Intermittent claudication: Clinical effectiveness of endovascular revascularization versus supervised hospital-based exercise training-randomized controlled trial (Article)

2009-02-01T00:00:00Z

Purpose: To compare clinical success, functional capacity, and quality of life during 12 months after revascularization or supervised exercise training in patients with intermittent claudication. Materials and Methods: This study had institutional review board approval, and all patients gave written informed consent. Between September 2002 and September 2005, 151 consecutive patients who presented with symptoms of intermittent claudication were randomly assigned to undergo either endovascular revascularization (angioplasty-first approach) (n = 76) or hospital-based supervised exercise (n = 75). The outcome measures were clinical success, functional capacity, and quality of life after 6 and 12 months. Clinical success was defined as improvement in at least one category in the Rutherford scale above the pretreatment level. Significance of differences between the groups was assessed with the unpaired τ test, x2 test, or Mann-Whitney U test. To adjust outcomes for imbalances of baseline values, multi-variable regression analysis was performed. Results: Immediately after the start of treatment, patients who underwent revascularization improved more than patients who performed exercise in terms of clinical success (adjusted odds ratio [OR], 39; 99% confidence interval [CI]: 11, 131; P <.001), but this advantage was lost after 6 (adjusted OR, 0.9; 99% CI: 0.3, 2.3; P = .70) and 12 (adjusted OR, 1.1; 99% CI: 0.5, 2.8; P = .73) months. After revascularization, fewer patients showed signs of ipsilateral symptoms at 6 months compared with patients in the exercise group (adjusted OR, 0.4; 99% CI: 0.2, 0.9; P <.001), but no significant differences were demonstrated at 12 months. After both treatments, functional capacity and quality of life scores increased after 6 and 12 months, but no significant differences between the groups were demonstrated. Conclusion: After 6 and 12 months, patients with intermittent claudication benefited equally from either endovascular revascularization or supervised exercise. Improvement was, however, more immediate after revascularization.

A comparison between willingness to pay and willingness to give up time (Article)

2009-02-01T00:00:00Z

We compared the willingness-to-pay and willingness to give up time methods to assess preferences for digital subtraction angiography (DSA), computed tomography angiography (CTA) and magnetic resonance angiography (MRA). Respondents were hypertensive patients suspected of having renal artery stenosis. Data were gathered using telephone interviews. Both the willingness-to-pay and willingness to give up time methods revealed that patients preferred CTA to MRA in order to avoid DSA. The agreement between willingness-to-pay and willingness to give up time responses was high (kappa 0.65-0.85). The willingness-to-pay method yielded relatively more protest answers (12%) as compared to willingness to give up time (2%). So, our results provided evidence for the comparability of willingness to pay and willingness to give up time. The high percentage of protest answers on the willingness-to-pay questions raises questions with respect to the application of the willingness-to-pay method in a broad decision-making context. On the other hand, the strength of willingness-to-pay is that the method directly arrives at a monetary measure well founded in economic theory, whereas the willingness to give up time method requires conversion to monetary units.

Evidence-based radiology: why and how? (Article)

2009-01-01T00:00:00Z

Purpose: To provide an overview of evidence-based medicine (EBM) in relation to radiology and to define a policy for adoption of this principle in the European radiological community. Results: Starting from Sackett's definition of EBM we illustrate the top-down and bottom-up approaches to EBM as well as EBM's limitations. Delayed diffusion and peculiar features of evidence-based radiology (EBR) are defined with emphasis on the need to shift from the demonstration of the increasing ability to see more and better, to the demonstration of a significant change in treatment planning or, at best, of a significant gain in patient outcome. The "as low as reasonably achievable" (ALARA) principle is thought as a dimension of EBR while EBR is proposed as part of the core curriculum of radiology residency. Moreover, we describe the process of health technology assessment in radiology with reference to the six-level scale of hierarchy of studies on diagnostic tests, the main sources of bias in studies on diagnostic performance, and levels of evidence and degrees of recommendations according to the Centre for Evidence-Based Medicine (Oxford, UK) as well as the approach proposed by the GRADE working group. Problems and opportunities offered by evidence-based guidelines in radiology are considered. Finally, we suggest nine points to be actioned by the ESR in order to promote EBR. Conclusion: Radiology will benefit greatly from the improvement in practice that will result from adopting this more rigorous approach to all aspects of our work.

Diagnostic Accuracy of 64-Slice Computed Tomography Coronary Angiography. A Prospective, Multicenter, Multivendor Study (Article)

2008-12-16T00:00:00Z

Objectives: This study sought to determine the diagnostic accuracy of 64-slice computed tomographic coronary angiography (CTCA) to detect or rule out significant coronary artery disease (CAD). Background: CTCA is emerging as a noninvasive technique to detect coronary atherosclerosis. Methods: We conducted a prospective, multicenter, multivendor study involving 360 symptomatic patients with acute and stable anginal syndromes who were between 50 and 70 years of age and were referred for diagnostic conventional coronary angiography (CCA) from September 2004 through June 2006. All patients underwent a nonenhanced calcium scan and a CTCA, which was compared with CCA. No patients or segments were excluded because of impaired image quality attributable to either coronary motion or calcifications. Patient-, vessel-, and segment-based sensitivities and specificities were calculated to detect or rule out significant CAD, defined as ≥50% lumen diameter reduction. Results: The prevalence among patients of having at least 1 significant stenosis was 68%. In a patient-based analysis, the sensitivity for detecting patients with significant CAD was 99% (95% confidence interval [CI]: 98% to 100%), specificity was 64% (95% CI: 55% to 73%), positive predictive value was 86% (95% CI: 82% to 90%), and negative predictive value was 97% (95% CI: 94% to 100%). In a segment-based analysis, the sensitivity was 88% (95% CI: 85% to 91%), specificity was 90% (95% CI: 89% to 92%), positive predictive value was 47% (95% CI: 44% to 51%), and negative predictive value was 99% (95% CI: 98% to 99%). Conclusions: Among patients in whom a decision had already been made to obtain CCA, 64-slice CTCA was reliable for ruling out significant CAD in patients with stable and unstable anginal syndromes. A positive 64-slice CTCA scan often overestimates the severity of atherosclerotic obstructions and requires further testing to guide patient management.

Cost-effectiveness of new cardiac and vascular rehabilitation strategies for patients with coronary artery disease (Article)

2008-12-09T00:00:00Z

Objective: Peripheral arterial disease (PAD) often hinders the cardiac rehabilitation program. The aim of this study was evaluating the relative cost-effectiveness of new rehabilitation strategies which include the diagnosis and treatment of PAD in patients with coronary artery disease (CAD) undergoing cardiac rehabilitation. Data Sources: Best-available evidence was retrieved from literature and combined with primary data from 231 patients. Methods: We developed a Markov decision model to compare the following treatment strategies: 1. cardiac rehabilitation only; 2. ankle-brachial index (ABI) if cardiac rehabilitation fails followed by diagnostic work-up and revascularization for PAD if needed; 3. ABI prior to cardiac rehabilitation followed by diagnostic work-up and revascularization for PAD if needed. Quality-adjusted-life years (QALYs), life-time costs (US $), incremental cost-effectiveness ratios (ICER), and gain in net health benefits (NHB) in QALY equivalents were calculated. A threshold willingness-to-pay of $75 000 was used. Results: ABI if cardiac rehabilitation fails was the most favorable strategy with an ICER of $44 251 per QALY gained and an incremental NHB compared to cardiac rehabilitation only of 0.03 QALYs (95% CI: -0.17, 0.29) at a threshold willingness-topay of $75 000/ QALY. After sensitivity analysis, a combined cardiac and vascular rehabilitation program increased the success rate and would dominate the other two strategies with total lifetime costs of $30 246 a quality-adjusted life expectancy of 3.84 years, and an incremental NHB of 0.06 QALYs (95%CI:-0.24, 0.46) compared to current practice. The results were robust for other different input parameters. Conclusion: ABI measurement if cardiac rehabilitation fails followed by a diagnostic work-up and revascularization for PAD if needed are potentially cost-effective compared to cardiac rehabilitation only.

Cost-effectiveness analysis: Some clarifications (Article)

2008-12-01T00:00:00Z

Cost-effectiveness of endovascular revascularization compared to supervised hospital-based exercise training in patients with intermittent claudication: A randomized controlled trial (Article)

2008-12-01T00:00:00Z

Background: The optimal first-line treatment for intermittent claudication is currently unclear. Objective: To compare the cost-effectiveness of endovascular revascularization vs supervised hospital-based exercise in patients with intermittent claudication during a 12-month follow-up period. Design: Randomized controlled trial with patient recruitment between September 2002-September 2006 and a 12-month follow-up per patient. Setting: A large community hospital. Participants: Patients with symptoms of intermittent claudication due to an iliac or femoro-popliteal arterial lesion (293) who fulfilled the inclusion criteria (151) were recruited. Excluded were, for example, patients with lesions unsuitable for revascularization (iliac or femoropopliteal TASC-type D and some TASC type-B/C. Intervention: Participants were randomly assigned to endovascular revascularization (76 patients) or supervised hospital-based exercise (75 patients). Measurements: Mean improvement of health-related quality-of-life and functional capacity over a 12-month period, cumulative 12-month costs, and incremental costs per quality-adjusted life year (QALY) were assessed from the societal perspective. Results: In the endovascular revascularization group, 73% (55 patients) had iliac disease vs 27% (20 patients) femoral disease. Stents were used in 46/71 iliac lesions (34 patients) and in 20/40 femoral lesions (16 patients). In the supervised hospital-based exercise group, 68% (51 patients) had iliac disease vs 32% (24 patients) with femoral disease. There was a non-significant difference in the adjusted 6- and 12-month EuroQol, rating scale, and SF36-physical functioning values between the treatment groups. The gain in total mean QALYs accumulated during 12 months, adjusted for baseline values, was not statistically different between the groups (mean difference revascularization versus exercise 0.01; 99% CI -0.05, 0.07; P = .73). The total mean cumulative costs per patient was significantly higher in the revascularization group (mean difference €2318; 99% CI €2130, € 2506; P < .001) and the incremental cost per QALY was 231 800 €/QALY adjusted for the baseline variables. One-way sensitivity analysis demonstrated improved effectiveness after revascularization (mean difference 0.03; CI 0.02, 0.05; P < .001), making the incremental costs 75 208 €/QALY. Conclusion: In conclusion, there was no significant difference in effectiveness between endovascular revascularization compared to supervised hospital-based exercise during 12-months follow-up, any gains with endovascular revascularization found were non-significant, and endovascular revascularization costs more than the generally accepted threshold willingness-to-pay value, which favors exercise.

Assessment of feasibility of endovascular treatment of ruptured intracranial aneurysms with 16-detector row CT angiography (Article)

2008-11-01T00:00:00Z

Background: It is unclear whether 16-detector row CT angiography (CTA) can replace digital subtraction angiography (DSA) to assess the feasibility of endovascular treatment (EVT) in the acute phase after aneurysmal subarachnoid hemorrhage. Methods: We studied 80 consecutive patients with aneurysmal subarachnoid hemorrhage, who underwent both CTA and DSA. Two interventional neuroradiologists independently scored CTA and, immediately thereafter, DSA with respect to feasibility of EVT. We determined whether CTA without DSA was sufficient for a definite judgment. We also assessed interobserver agreement. Results: The 2 readers judged EVT to be feasible in 24 and 37 patients with CTA alone and not feasible in 34 and 20 patients. In these patients, DSA yielded additional information in 6 (reader 1) and 5 patients (reader 2), which did not affect treatment decision. In 19 and 7 patients, DSA was considered inferior to CTA. In the remaining patients (n = 22 and 23, respectively), feasibility of EVT could not be judged with CTA alone, and DSA results were required in addition for a treatment decision. Interobserver agreement on feasibility of EVT was just fair (κ <0.40). Conclusions: In our series of patients, 16-detector row CTA was a reliable investigation to assess feasibility of EVT of ruptured intracranial aneurysms in most patients. Further, we found that interobserver disagreement on feasibility of EVT was considerable.

Meta-analysis of summary survival curve data (Article)

2008-09-30T00:00:00Z

The use of standard univariate fixed- and fandom-effects models in meta-analysis has become well known in the last 20 years. However, these models are unsuitable for meta-analysis of clinical trials that present multiple survival estimates (usually illustrated by a survival curve) during a follow-up period. Therefore, special methods are needed to combine the survival curve data from different trials in a meta-analysis. For this purpose, only fixed-effects models have been suggested in the literature. In this paper, we propose a multivariate random-effects model for joint analysis of survival proportions reported at multiple time points and in different studies, to be combined in a meta-analysis. The model could be seen as a generalization of the fixed-effects model of Dear (Biometrics 1994; 50:989-1002). We illustrate the method by using a simulated data example as well as using a clinical data example of meta-analysis with aggregated survival curve data. All analyses can be carried out with standard general linear MIXED model software.

Bivariate random effects meta-analysis of ROC curves (Article)

2008-09-01T00:00:00Z

Meta-analysis of receiver operating characteristic (ROC)-curve data is often done with fixed-effects models, which suffer many shortcomings. Some random-effects models have been proposed to execute a meta-analysis of ROC-curve data, but these models are not often used in practice. Straightforward modeling techniques for multivariate random-effects meta-analysis of ROC-curve data are needed. The 1st aim of this article is to present a practical method that addresses the drawbacks of the fixedeffects summary ROC (SROC) method of Littenberg and Moses. Sensitivities and specificities are analyzed simultaneously using a bivariate random-effects model. The 2nd aim is to show that other SROC curves can also be derived from the bivariate model through different characterizations of the estimated bivariate normal distribution. Thereby the authors show that the bivariate random-effects approach not only extends the SROC approach but also provides a unifying framework for other approaches. The authors bring the statistical meta-analysis of ROC-curve data back into a framework of relatively standard multivariate meta-analysis with random effects. The analyses were carried out using the software package SAS (Proc NLMIXED).

Preference-based quality of life of patients on renal replacement therapy: A systematic review and meta-analysis (Article)

2008-07-01T00:00:00Z

Objectives: Various utility measures have been used to assess preference-based quality of life of patients with end-stage renal disease (ESRD). The purposes of this study were to summarize the literature on utilities of hemodialysis (HD), peritoneal dialysis (PD), and renal transplantation (RTx) patients, to compare utilities between these patient groups, and to obtain estimates for quality-of-life adjustment in economic analyses. Methods: We searched the English literature for studies that reported visual analog scale (VAS), time trade-off (TTO), standard gamble (SG), EuroQol-5D (EQ-5D), and health utilities index (HUI) values of ESRD patients. We extracted patient characteristics and utilities and calculated mean utilities and 95% confidence intervals (CIs) for categories defined by utility measure and treatment modality using random-effects models. Results: We identified 27 articles that met the inclusion criteria. VAS articles were too heterogeneous to summarize quantitatively and we found only one study reporting HUI values. Thus, we summarized utilities from TTO, SG, and EQ-5D studies. Mean TTO and EQ-5D-index values were lower for dialysis compared to RTx patients, though not statistically significant for TTO values (TTO values: HD 0.61, 95% CI 0.54-0.68; PD 0.73, 95% CI 0.61-0.85; RTx 0.78, 95% CI 0.63-0.93; EQ-5D-index values: HD 0.56, 95% CI 0.49-0.62; PD 0.58, 95% CI 0.50-0.67; RTx 0.81, 95% CI 0.72-0.90). Mean HD versus PD associated TTO, EQ-5D-index and EQ-VAS values were not statistically significantly different. Conclusion: RTx patients tended to have a higher utility than dialysis patients. Among HD and PD patients, there were no statistically significant differences in utility.

Dual source coronary computed tomography angiography for detecting in-stent restenosis (Article)

2008-07-01T00:00:00Z

Objective: To evaluate the performance of dual source CT coronary angiography (DSCT-CA) in the detection of instent restenosis (≥50% luminal narrowing) in symptomatic patients referred for conventional angiography (CA). Design/patients: 100 patients (78 males, age 62 (SD 10)) with chest pain were prospectively evaluated after coronary stenting. DSCT-CA was performed before CA. Setting: Many patients undergo coronary artery stenting; availability of a non-invasive modality to detect in-stent restenosis would be desirable. Results: Average heart rate (HR) was 67 (SD 12) (range 46-106) bpm. There were 178 stented lesions. The interval between stenting and inclusion in the study was 35 (SD 41) (range 3-140) months. 39/100 (39%) patients had angiographically proven restenosis. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of DSCT-CA, calculated in all stents, were 94%, 92%, 77% and 98%, respectively. Diagnostic performance at HR <70 bpm (n = 69; mean 58 bpm) was similar to that at HR ≥70 bpm (n = 31; mean 78 bpm); diagnostic performance in single stents (n = 95) was similar to that in overlapping stents and bifurcations (n = 83). In stents ≥3.5 mm (n = 78), sensitivity, specificity, PPV, NPV were 100%; in 3 mm stents (n = 59), sensitivity and NPV were 100%, specificity 97%, PPV 91%; in stents ≤2.75 mm (n = 41), sensitivity was 84%, specificity 64%, PPV 52%, NPV 90%. Nine stents ≤2.75 mm were uninterpretable. Specificity of DSCT-CA in stents ≥3.5 mm was significantly higher than in stents ≤2.75 mm (OR = 6.14; 99%CI: 1.52 to 9.79). Conclusion: DSCT-CA performs well in the detection of in-stent restenosis. Although DSCT-CA leads to frequent false positive findings in smaller stents (≤2.75 mm), it reliably rules out in-stent restenosis irrespective of stent size.

Complex vascular anatomy in live kidney donation: Imaging and consequences for clinical outcome (Article)

2008-06-27T00:00:00Z

BACKGROUND.: Live donor kidneys with multiple arteries are associated with surgical complexity for removal and increased rate of recipient ureteral complications. We evaluated the outcome of vascular imaging and the clinical consequences of multiple arteries and veins. METHODS.: From 2001 to 2005 data of 288 live kidney donations and transplantations were prospectively collected. Vascular anatomy at operation was compared with vascular anatomy as imaged by magnetic resonance imaging (MRI) or subtraction angiography, and consequences of multiple vessels were investigated. RESULTS.: Simple renal anatomy with a solitary artery and vein was present in 208 (72%) kidneys. Sixty (21%) transplants had multiple arteries. Thirty (10%) transplants had multiple veins. Magnetic resonance imaging failed to predict arterial anatomy in 23 of 220 donors (10%) compared with 3 of 101 (3%) after angiography. The presence of multiple veins did not influence outcomes after nephrectomy in general. Multiple arteries did not affect clinical outcomes in open donor nephrectomy (n=103). In laparoscopic donor nephrectomy (n=185) multiple arteries were associated with longer operation times (245 vs. 221 min, P=0.023) and increased blood loss (225 vs. 220 mL, P=0.029). In general, neither multiple arteries nor vascular reconstructions influenced recipient creatinine clearance or ureteral complication rate. However, accessory arteries to the lower pole correlated with an increased rate of ureteral complications (47% vs. 14%, P=0.01). CONCLUSIONS.: Multiple arteries may increase operation time. Accessory lower pole arteries are associated with a higher rate of recipient ureteral complications indicating the importance of arterial imaging. Currently, both magnetic resonance imaging and angiography provide suboptimal information on renal vascular anatomy.

Multicenter randomized controlled trial of the costs and effects of noninvasive diagnostic imaging in patients with peripheral arterial disease: The DIPAD trial (Article)

2008-05-01T00:00:00Z

OBJECTIVE. The purpose of our study was to compare the costs and effects of three noninvasive imaging tests as the initial imaging test in the diagnostic workup of patients with peripheral arterial disease. MATERIALS AND METHODS. Of 984 patients assessed for eligibility, 514 patients with peripheral arterial disease were randomized to MR angiography (MRA) or duplex sonography in three hospitals and to MRA or CT angiography (CTA) in one hospital. The outcome measures included the clinical utility, functional patient outcomes, quality of life, and actual diagnostic and therapeutic costs related to the initial imaging test during 6 months of follow-up. RESULTS. With adjustment for potentially predictive baseline variables, the learning curve, and hospital setting, a significantly higher confidence and less additional imaging were found for MRA and CTA compared with duplex sonography. No statistically significant differences were found in improvement in functional patient outcomes and quality of life among the groups. The total costs were significantly higher for MRA and duplex sonography than for CTA. CONCLUSION. The results suggest that both CTA and MRA are clinically more useful than duplex sonography and that CTA leads to cost savings compared with both MRA and duplex sonography in the initial imaging evaluation of peripheral arterial disease.

Effectiveness of acupuncture-type interventions versus expectant management to correct breech presentation: A systematic review (Article)

2008-04-01T00:00:00Z

Objective: A systematic review of studies assessing the effectiveness of acupuncture-type interventions (moxibustion, acupuncture, or electro-acupuncture) on acupuncture point BL 67 to correct breech presentation compared to expectant management, based on controlled trials. Data sources: Articles published from 1980 to May 2007 in databases of Medline, EMBASE, the Cochrane Central Register of Controlled Trials, AMED, NCCAM, Midirs and reference lists. Study selection: Studies included were original articles; randomised controlled trials (RCT) or controlled cohort studies; acupuncture-type intervention on BL 67 compared with expectant management; ultrasound confirmed breech presentation and position of the fetus after treatment confirmed with ultrasound, position at delivery, and/or the proportion of caesarean sections reported. Data extraction: Three reviewers independently extracted data. Disagreements were resolved by consensus. Data synthesis: Of 65 retrieved citations, six RCT's and three cohort studies fulfilled the inclusion criteria. Data were pooled using random-effects models. In the RCT's the pooled proportion of breech presentations was 34% (95% CI: 20-49%) following treatment versus 66% (95% CI: 55-77%) in the control group (OR 0.25 95% CI: 0.11-0.58). The pooled proportion in the cohort studies was 15% (95% CI: 1-28%) versus 36% (95% CI: 14-58%), (OR 0.29, 95% CI: 0.19-0.43). Including all studies the pooled proportion was 28% (95% CI: 16-40%) versus 56% (95% CI: 43-70%) (OR 0.27, 95% CI: 0.15-0.46). Conclusions: Our results suggest that acupuncture-type interventions on BL 67 are effective in correcting breech presentation compared to expectant management. Some studies were of inferior quality to others and further RCT's of improved quality are necessary to adequately answer the research question.

Outcome after Complicated Minor Head Injury (Article)

2008-03-01T00:00:00Z

BACKGROUND AND PURPOSE: Functional outcome in patients with minor head injury with neurocranial traumatic findings on CT is largely unknown. We hypothesized that certain CT findings may be predictive of poor functional outcome. Materials and METHODS: All patients from the CT in Head Injury Patients (CHIP) study with neurocranial traumatic CT findings were included. The CHIP study is a prospective, multicenter study of consecutive patients, > or =16 years of age, presenting within 24 hours of blunt head injury, with a Glasgow Coma Scale (GCS) score of 13-14 or a GCS score of 15 and a risk factor. Primary outcome was functional outcome according to the Glasgow Outcome Scale (GOS). Other outcome measures were the modified Rankin Scale (mRS), the Barthel Index (BI), and number and severity of postconcussive symptoms. The association between CT findings and outcome was assessed by using univariable and multivariable regression analysis. RESULTS: GOS was assessed in 237/312 patients (76%) at an average of 15 months after injury. There was full recovery in 150 patients (63%), moderate disability in 70 (30%), severe disability in 7 (3.0%), and death in 10 (4.2%). Outcome according to the mRS and BI was also favorable in most patients, but 82% of patients had postconcussive symptoms. Evidence of parenchymal damage was the only independent predictor of poor functional outcome (odds ratio = 1.89, P = .022). CONCLUSION: Patients with neurocranial complications after minor head injury generally make a good functional recovery, but postconcussive symptoms may persist. Evidence of parenchymal damage on CT was predictive of poor functional outcome.

Uncertainty and sensitivity analyses of a dynamic economic evaluation model for vaccination programs (Article)

2008-03-01T00:00:00Z

With public health policy increasingly relying on mathematical models to provide insights about the impacts of potential policy options, the demand for uncertainty and sensitivity analyses that explore the implications of different assumptions in a model continues to expand. Although analysts continue to develop methods to meet the demand, most modelers rely on a single method in the context of their assessments and presentations of results, and few analysts provide results that facilitate comparisons between uncertainty and sensitivity analysis methods. Methods vary in their degree of analytical difficulty and in the nature of the information that they provide, and analysts should communicate results with a note that not all methods yield the same insights. The authors explore several sensitivity analysis methods to test whether the choice of method affects the insights and importance rankings of inputs from the analysis. They use a dynamic cost-effectiveness model of a hypothetical infectious disease as the basis to perform 1-way and multi-way sensitivity analyses, design of experiments, and Morris' method. They also compute partial derivatives as well as a number of probabilistic sensitivity measures, including correlations, regression coefficients, and the correlation ratio, to demonstrate the existing methods and to compare them. The authors find that the magnitudes and rankings of sensitivity measures depend on the selected method(s) and make recommendations regarding the choice of method depending on the complexity of the model, number of uncertain inputs, and desired types of insights from the sensitivity analysis.

The association of arterial stiffness and arterial calcification: The Rotterdam Study (Article)

2008-03-01T00:00:00Z

Staging investigations for oesophageal cancer: A meta-analysis (Article)

2008-02-12T00:00:00Z

The aim of the study was to compare the diagnostic performance of endoscopic ultrasonography (EUS), computed tomography (CT), and18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in staging of oesophageal cancer. PubMed was searched to identify English-language articles published before January 2006 and reporting on diagnostic performance of EUS, CT, and/or FDG-PET in oesophageal cancer patients. Articles were included if absolute numbers of true-positive, false-negative, false-positive, and true-negative test results were available or derivable for regional, celiac, and abdominal lymph node metastases and/or distant metastases. Sensitivities and specificities were pooled using a random effects model. Summary receiver operating characteristic analysis was performed to study potential effects of study and patient characteristics. Random effects pooled sensitivities of EUS, CT, and FDG-PET for regional lymph node metastases were 0.80 (95% confidence interval 0.75-0.84), 0.50 (0.41-0.60), and 0.57 (0.43-0.70), respectively, and specificities were 0.70 (0.65-0.75), 0.83 (0.77-0.89), and 0.85 (0.76-0.95), respectively. Diagnostic performance did not differ significantly across these tests. For detection of celiac lymph node metastases by EUS, sensitivity and specificity were 0.85 (0.72-0.99) and 0.96 (0.92-1.00), respectively. For abdominal lymph node metastases by CT, these values were 0.42 (0.29-0.54) and 0.93 (0.86-1.00), respectively. For distant metastases, sensitivity and specificity were 0.71 (0.62-0.79) and 0.93 (0.89-0.97) for FDG-PET and 0.52 (0.33-0.71) and 0.91 (0.86-0.96) for CT, respectively. Diagnostic performance of FDG-PET for distant metastases was significantly higher than that of CT, which was not significantly affected by study and patient characteristics. The results suggest that EUS, CT, and FDG-PET each play a distinctive role in the detection of metastases in oesophageal cancer patients. For the detection of regional lymph node metastases, EUS is most sensitive, whereas CT and FDG-PET are more specific tests. For the evaluation of distant metastases, FDG-PET has probably a higher sensitivity than CT. Its combined use could however be of clinical value, with FDG-PET detecting possible metastases and CT confirming or excluding their presence and precisely determining the location(s).

Value of information analysis used to determine the necessity of additional research: MR imaging in acute knee trauma as an example (Article)

2008-02-01T00:00:00Z

Purpose: To help guide future outcomes research regarding the use of magnetic resonance (MR) imaging in patients with acute knee trauma in an emergency department setting, with use of prospective data from a randomized clinical trial and value of information analysis. Materials and Methods: A total of 189 patients (123 male, 66 female; mean age, 33.4 years) were randomly assigned to undergo radiography alone (n = 93) or radiography and MR imaging (n = 96). Institutional review board approval and informed consent (parental consent for minors) were obtained. During 6 months of follow-up, data on quality of life and 39 cost parameters were collected. Value-of-information analysis was used to estimate the expected benefit of future research to eliminate the decision uncertainty that remained after trial completion. In addition, the parameters that were responsible for most of the decision uncertainty were identified, the expected benefits of various study designs were evaluated, and the optimal sample size was estimated. Results: Only three parameters were responsible for most of the decision uncertainty: number of quality-adjusted life-years, cost of an overnight hospital stay, and friction costs. A study in which data on these three parameters are gathered would have an optimal sample size of 3500 patients per arm and would be expected to result in a societal benefit of €5.6 million or 70 quality-adjusted life-years. Conclusion: The optimal study design for use of MR imaging to evaluate acute knee trauma involves a trial in which there are 3500 patients per trial arm, and data on the number of quality-adjusted life-years, cost of an overnight hospital stay, and friction costs are collected.

Diagnostic performance of coronary CT angiography by using different generations of multisection scanners: Single-center experience (Article)

2008-02-01T00:00:00Z

Purpose: To retrospectively compare sensitivity and specificity of four generations of multidetector computed tomographic (CT) scanners for diagnosing significant (≥50%) coronary artery stenosis, with quantitative conventional coronary angiography as reference standard. Materials and Methods: The institutional review board approved this study. All patients consented to undergo CT studies prior to conventional coronary angiography, after they were informed of the additional radiation dose, and to the use of their data for future retrospective research. Two hundred four patients (157 men, 47 women; mean age, 58 years ± 11 [standard deviation]), classified in four groups of 51 patients each, underwent coronary CT angiography with four-section, first- and second-generation 16-section, and 64-section CT scanners. Patients in sinus rhythm scheduled for conventional coronary angiography (stable angina, atypical chest pain) were included. Patients with bypass grafts and stents were excluded. Two readers unaware of results of conventional coronary angiography evaluated CT scans. Coronary artery segments of 2 mm or larger in diameter were included for comparative evaluation with quantitative coronary angiography. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for detection of significant stenoses (≥50% luminal diameter reduction) were calculated. Results: Image quality was rated poor for the following percentages of coronary artery segments: 33.1% at four-section CT, 14.4% at first-generation 16-section CT, 6.3% at second-generation 16-section CT, and 2.6% at 64-section CT. Sensitivity, specificity, PPV, and NPV, respectively, were as follows: 57%, 91%, 60%, and 90% at four-section CT; 90%, 93%, 65%, and 99% at first-generation 16-section CT; 97%, 98%, 87%, and 100% at second-generation 16-section CT; and 99%, 96%, 80%, and 100% at 64-section CT. Diagnostic performance of four-section CT was significantly poorer than that of second-generation 16-section CT (odds ratio = 4.57) and 64-section CT (odds ratio = 2.89). Conclusion: Diagnostic performance of coronary CT angiography varies among scanners of different generations. Earlier-generation scanners (four sections) had significantly poorer performance; performance of 16- compared with 64-section CT scanners showed progressive, although not significant, improvement.

Minor head injury: Guidelines for the Use of CT - A Multicenter Validation Study (Article)

2007-12-01T00:00:00Z

Abstract PURPOSE: To prospectively and externally validate published national and international guidelines for the indications of computed tomography (CT) in patients with a minor head injury. MATERIALS AND METHODS: The study protocol was institutional review board approved. All patients implicitly consented to use of their deidentified data for research purposes. Between February 2002 and August 2004, data were collected in consecutive adult patients with blunt minor head injury (Glasgow Coma Scale score of 13-14 or 15) and a risk factor for neurocranial traumatic complications at presentation at four Dutch university hospitals. Primary outcome was any neurocranial traumatic CT finding. Secondary outcomes were clinically relevant traumatic CT findings and neurosurgical intervention. Sensitivity and specificity of each guideline for all outcomes and the number of patients needed to scan to detect one outcome (ie, the number of patients needed to undergo CT to find one patient with a neurocranial traumatic CT finding, a clinically relevant traumatic CT finding, or a CT finding that required neurosurgical intervention) were estimated. RESULTS: Data were available for 3181 patients. Only the European Federation of Neurological Societies guidelines reached a sensitivity of 100% for all outcomes. Specificity was 0.0%-0.5%. The Dutch guidelines had the lowest sensitivity (76.5%) for neurosurgical interventions. The best specificities for traumatic CT findings and neurosurgical interventions were reached with the criteria proposed by the United Kingdom National Institute for Clinical Excellence (NICE) (46.1% and 43.6%, respectively), albeit at relatively low sensitivities (82.1% and 94.1%, respectively). The number of patients needed to scan ranged from six to 13 for traumatic CT findings and from 79 to 193 for neurosurgical interventions. CONCLUSION: All validated guidelines demonstrated a trade-off between sensitivity and specificity. The lowest number of patients needed to scan for either of the outcomes was reached with the NICE criteria. Supplemental material: radiology.rsnajnls.org/cgi/content/full/2452061509/DC1

Multi-detector row computed tomography angiography of peripheral arterial disease (Article)

2007-12-01T00:00:00Z

With the introduction of multi-detector row computed tomography (MDCT), scan speed and image quality has improved considerably. Since the longitudinal coverage is no longer a limitation, multi-detector row computed tomography angiography (MDCTA) is increasingly used to depict the peripheral arterial runoff. Hence, it is important to know the advantages and limitations of this new non-invasive alternative for the reference test, digital subtraction angiography. Optimization of the acquisition parameters and the contrast delivery is important to achieve a reliable enhancement of the entire arterial runoff in patients with peripheral arterial disease (PAD) using fast CT scanners. The purpose of this review is to discuss the different scanning and injection protocols using 4-, 16-, and 64-detector row CT scanners, to propose effective methods to evaluate and to present large data sets, to discuss its clinical value and major limitations, and to review the literature on the validity, reliability, and cost-effectiveness of multi-detector row CT in the evaluation of PAD.

Lower extremity arterial disease: Multidetector CT angiography - Meta-analysis (Article)

2007-11-01T00:00:00Z

Purpose: To obtain the best available estimates of the diagnostic performance of multidetector computed tomographic (CT) angiography compared with that of digital subtraction angiography (DSA) in the assessment of symptomatic lower extremity arterial disease and to identify the most important sources of variation in diagnostic performance between studies. Materials and Methods: Reports of studies published from January 2000 through April 2006 in English, German, French, or Spanish were searched for by using the MEDLINE, EMBASE, and Cochrane databases. Studies were included if they allowed construction of 2 X 2 contingency tables for the detection of stenosis of 50% or greater at multidetector CT angiography compared with that at DSA - the reference standard - in patients with claudication or critical ischemia. Two observers extracted data about study design, patient characteristics, arterial tracts, and technical protocols. Random-effects summary receiver operating characteristic analysis was performed to examine the influence of these data on diagnostic performance. Results: Of the 70 studies initially identified, 12 were included in which multidetector CT angiography was used to evaluate 9541 arterial segments in 436 patients. The pooled sensitivity and specificity for detecting a stenosis of at least 50% per segment were 92% (95% confidence interval: 89%, 95%) and 93% (9S% confidence interval: 91%, 95%), respectively. Three studies provided data about the diagnostic performance of multidetector CT angiography in subdivisions of the arterial tract. The diagnostic performance of multidetector CT angiography in the infrapopliteal tract was lower than but not significantly different from that in the aortoiliac (P > .11) and femoropopliteal (P > .40) tracts. Regression analysis showed that diagnostic performance was not significantly influenced by differences in study characteristics. Conclusion: Multidetector CT angiography is an accurate diagnostic test in the assessment of arterial disease (≥50% stenosis) of the entire lower extremity.

Ruptured abdominal aortic aneurysms: Endovascular repair versus open surgery - Systematic review (Article)

2007-10-01T00:00:00Z

Purpose: To perform a systematic review of studies in which endovascular repair was compared with open surgery in the treatment of patients with a ruptured abdominal aortic aneurysm (AAA). Materials and Methods: A search of the English-language literature from January 1994 until March 2006 was performed. Inclusion criteria for studies were that they were about a comparison between patients who underwent endovascular repair and patients who underwent open surgery, that each treatment group included at least five patients, that information about patients' hemodynamic condition at presentation was reported, and that 30-day mortality was reported for each treatment group. Two reviewers independently extracted the data, and discrepancies were resolved by an arbiter. Random-effects models and meta-regression analysis were used to calculate crude and adjusted odds ratios (ORs) for endovascular repair versus open surgery. Ten studies, in which the results of 478 procedures (n = 148 for endovascular repair, n = 330 for open surgery) were reported, met the inclusion criteria. All studies were observational; no randomized controlled trials were found. The pooled 30-day mortality was 22% (95% confidence interval [CI]: 16%, 29%) for endovascular repair and 38% (95% CI: 32%, 45%) for open surgery. The pooled rate for total systemic complications was 28% (95% CI: 17%, 48%) for endovascular repair and 56% (95% CI: 37%, 85%) for open surgery. The crude OR for 30-day mortality for endovascular repair compared with open surgery was 0.45 (95% CI: 0.28, 0.72). After adjustment for patients' hemodynamic condition, the OR was 0.67 (95% CI: 0.31, 1.44). Conclusion: In this systematic review, after adjustment for patients' hemodynamic condition at presentation, a benefit in 30-day mortality for endovascular repair compared with open surgery for patients with a ruptured AAA was observed, but it was not statistically significant.

Quality of life assessed with the medical outcomes study short form 36-item health survey of patients on renal replacement therapy: A systematic review and meta-analysis (Article)

2007-09-01T00:00:00Z

Objectives: The Medical Outcomes Study Short Form 36-Item Health Survey (SF-36) is the most widely used generic instrument to estimate quality of life of patients on renal replacement therapy. Purpose of this study was to summarize and compare the published literature on quality of life of hemodialysis (HD), peritoneal dialysis (PD), and renal transplant (RTx) patients. Methods: We used random-effects regression analyses to compare the SF-36 scores across treatment groups and adjusted this comparison for age and prevalence of diabetes using random-effects meta-regression analyses. Results: We found 52 articles that met the inclusion criteria, reporting quality of life of 36,582 patients. The unadjusted scores of all SF-36 health dimensions were not significantly different between HD and PD patients, but the scores of RTx patients were higher than those of dialysis patients, except for the dimensions Mental Health and Bodily Pain. Point differences between dialysis and RTx patients varied from 2 to 32. With adjustment for age and diabetes, the differences became smaller (point difference 2–22). The significance of the differences of both dialysis groups compared with RTx recipients disappeared for the dimensions Vitality and Social Functioning. The significance of the differences between HD and RTx patients disappeared on the dimensions Physical Functioning, Role Physical, and Bodily Pain. Conclusion: We conclude that dialysis patients have a lower quality of life than RTx patients, but this difference can partly be explained by differences in age and prevalence of diabetes. Keywords: hemodialysis, meta-analysis, peritoneal dialysis, quality of life, renal transplantation.

Stress echocardiography, stress single-photon-emission computed tomography and electron beam computed tomography for the assessment of coronary artery disease: A meta-analysis of diagnostic performance (Article)

2007-09-01T00:00:00Z

Background: Many studies have been published on the diagnostic performance of noninvasive tests for the assessment of coronary artery disease. The objective of the present study was to compare the published literature on the diagnostic performance of stress echocardiography, stress single-photon-emission computed tomography (SPECT), and electron beam computed tomography (EBCT). Methods: Meta-analytic studies on the diagnostic performance of imaging tests for coronary artery disease were searched in the Cochrane Library, PubMed, and bibliographies of selected articles. Sensitivities, specificities, and diagnostic odds ratios of the source studies were calculated per modality. Taking into account differences between studies, a random effects summary receiver operating characteristic analysis was performed. Results: We analyzed the data of 351 patient series, which were reported in 11 meta-analyses. The sensitivity of EBCT was significantly higher than that of stress SPECT, which had a significantly higher sensitivity than stress echocardiography (respectively, 93.1% [95% confidence interval, 90.7-95.6], 88.1 [95% confidence interval, 86.6-89.6], and 79.1% [95% confidence interval, 77.6-80.5]). The specificity of stress echocardiography was significantly higher than that of stress SPECT, which had a significantly higher specificity than EBCT (respectively, 87.1% [95% confidence interval, 85.7-88.5], 73.0% [95% confidence interval, 69.1-76.9], and 54.5% [95% confidence interval, 45.3-63.8]). The diagnostic odds ratios did not differ significantly between the 3 modalities, which resulted in one underlying summary receiver operating characteristic curve. Conclusions: This study suggests that there are no significant differences in the overall diagnostic performance between stress echocardiography, stress SPECT, and EBCT for the diagnosis of coronary artery disease. However, differences exist in sensitivity and specificity estimates, which may make each modality useful in different settings.

MRI follow-up of posttraumatic bone bruises of the knee in general practice (Article)

2007-09-01T00:00:00Z

OBJECTIVE. Our purpose was to study the natural course of bone bruises in posttraumatic knees and to describe possible determinants of this course. SUBJECTS AND METHODS. Prospective MRI follow-up data were gathered for patients with bone bruises after sustained knee trauma. Follow-up ceased when the bone bruise could no longer be discerned or after 1 year of follow-up. For each patient we studied the relationships between time to healing of all bone bruises and the explanatory variables age, sex, obesity, workload, sports load, number of bone bruises, osteoarthritis, and concomitant knee lesions using survival analyses. We also investigated the relationships between resolution of individual bone bruises and lesion type, size and location, and the explanatory variables at 6 months and at 12 months separately, using logistic regression analyses for repeated measurements and generalized estimating equations. RESULTS. In 80 patients, 157 bone bruises were found. The estimated median healing time was 42.1 weeks. Healing was prolonged in patients having a higher number of bone bruises and in the presence of osteoarthritis. Resolution of individual bone bruises was prolonged in the presence of osteoarthritis and greater age. Reticular lesions were less likely to be present after 6 months than other bone bruise types. None of the remaining tested variables had prognostic value. CONCLUSION. Median healing time of bone bruises is 42.1 weeks. Prognosis is particularly influenced by the presence of osteoarthritis. Age, type of bone bruise, and number of bruises also have prognostic value.

Renal artery stenosis: Cost-effectiveness of diagnosis and treatment (Article)

2007-08-01T00:00:00Z

Purpose: To use a decision analytic model to determine the cost-effectiveness of performing diagnostic digital subtraction angiography (DSA), computed tomographic (CT) angiography, or magnetic resonance (MR) angiography or proceeding immediately to tentative percutaneous revascularization in patients suspected of having renovascular hypertension. Materials and Methods: With use of a Markov-Monte Carlo decision model, cost-effectiveness analysis was performed from a societal perspective. Data were derived from the Renal Artery Diagnostic Imaging Study in Hypertension and from published literature. The base-case analyses were used to evaluate a 50-year-old patient with a diastolic blood pressure higher than 95 mm Hg and one or more clinical clues suggestive of renovascular hypertension. Outcome measures were quality-adjusted life-year (QALY), lifetime costs, and incremental cost-effectiveness. Results: For a 50-year-old male patient, immediate tentative revascularization was the least costly (€54 415) and most effective (12.265 QALYs) strategy. For the other strategies, costs and QALYs, respectively, were €55 570 and 12.195 for DSA, €55 191 and 12.163 for CT angiography, and €56 890 and 12.088 for MR angiography. For a 50-year-old female patient, costs and QALYs, respectively, were €66 731 and 13.731 for MR angiography, €63 970 and 13.749 for CT angiography, and €63 079 and 13.902 for DSA. Immediate tentative revascularization yielded more QALYs (13.937) and was more costly (€63 329) than DSA. The incremental cost-effectiveness ratio was €7143 per QALY. As the prior probability increased, use of a more invasive diagnostic imaging strategy became justified. Also, the sensitivities of CT angiography and MR angiography and the costs of DSA influenced the results. Conclusion: Given currently accepted incremental cost-effectiveness ratios, immediate tentative percutaneous revascularization is a cost-effective strategy for the diagnosis of renal artery stenosis. Management decisions should be conditional on the prior probability.

Association between calcification in the coronary arteries, aortic arch and carotid arteries: The Rotterdam study (Article)

2007-08-01T00:00:00Z

Objective: The present study was performed to examine the prevalence of and associations between calcification in the coronary arteries, aortic arch and carotid arteries, assessed by multislice computed tomography (MSCT), in an elderly population. Methods and results: This study was part of the population-based Rotterdam study. From October 2003 until July 2004, subjects underwent a 16-slice MSCT scan. Calcification was quantified by calculating the Agatston, volume and mass score. Current analyses were performed in 600 subjects (mean age 74 years). The prevalences of calcification in the coronary and carotid arteries were higher in men compared to women. However, aortic arch calcification was more prevalent among women. In men, correlation coefficients based on the Agatston score ranged from 0.40 (between coronary and aortic arch calcification) to 0.54 (between aortic arch and carotid calcification) (p < 0.001). Correlation coefficients for women ranged from 0.30 (between coronary and aortic arch calcification) to 0.40 (between coronary and carotid calcification) (p < 0.001). Conclusions: While the prevalences of calcification in the coronary and the carotid arteries were higher in men compared to women, aortic arch calcification was more prevalent among women. Moderate to strong correlations between calcification in different vessel beds were found.

Diagnostic performance of multidetector CT angiography for assessment of coronary artery disease: Meta-analysis (Article)

2007-08-01T00:00:00Z

Purpose: To review the literature on the diagnostic performance of multidetector computed tomographic (CT) angiography for assessment of symptomatic coronary artery disease, with conventional coronary angiography as the reference standard. Materials and A PubMed and manual search of the literature published Methods: between January 1998 and May 2006 on use of multidetector CT angiography compared with coronary angiography in patients with symptomatic coronary artery disease was performed. Summary estimates of diagnostic odds ratio, sensitivity, and specificity were calculated. Random-effects models were used to compare the diagnostic performance of four-, 16-, and 64-detector CT angiographic units, and the proportion of nonassessable coronary arterial segments was evaluated. Results: Fifty-four studies were included in the meta-analysis: 22 studies with four-detector CT angiography, 26 with 16-detector CT angiography, and six with 64-detector CT angiography. The pooled sensitivity and specificity for detecting a greater than 50% stenosis per segment were 0.93 (95% confidence interval [CI]: 0.88, 0.97) and 0.96 (95% CI: 0.96, 0.97) for 64-detector CT angiography, 0.83 (95% CI: 0.76, 0.90) and 0.96 (95% CI: 0.95, 0.97) for 16-detector CT angiography, and 0.84 (95% CI: 0.81, 0.88) and 0.93 (95% CI: 0.91, 0.95) for four-detector CT angiography, respectively. Results of regression analysis indicated that the diagnostic performance significantly improved with the newer generations of multidetector CT scanners (64- and 16-detector vs four-detector units), adjusted for exclusion of nonassessable segments, and contrast agent concentration used (P < .05). Simultaneously, the nonassessable proportion of segments significantly decreased with the newer generations of multidetector CT scanners, adjusted for heart rate, prevalence of significant disease, and mean age. Conclusion: With the newer generations of multidetector CT scanners, the diagnostic performance for the assessment of coronary artery disease has significantly improved, and the proportion of nonassessable segments has decreased.

Validity of the Framingham point scores in the elderly: Results from the Rotterdam study (Article)

2007-07-01T00:00:00Z

Background: The National Cholesterol Education Program recommends assessing 10-year risk of coronary heart disease (CHD) in individuals free of established CHD with the Framingham Point Scores (FPS). Individuals with a risk >20% are classified as high risk and are candidates for preventive intervention. We aimed to validate the FPS in a European population of elderly subjects. Methods: Subjects free of established CHD at baseline were selected from the Rotterdam study, a population-based cohort of subjects 55 years or older in the Netherlands. We studied calibration, discrimination (c-index), and the accuracy of high-risk classifications. Events consisted of fatal CHD and nonfatal myocardial infarction. Results: Among 6795 subjects, 463 died because of CHD and 336 had nonfatal myocardial infarction. Predicted 10-year risk of CHD was on average well calibrated for women (9.9% observed vs 10.1% predicted) but showed substantial overestimation in men (14.3% observed vs 19.8% predicted), particularly with increasing age. This resulted in substantial number of false-positive classifications (specificity 70%) in men. In women, discrimination of the FPS was better than that in men (c-index 0.73 vs 0.63, respectively). However, because of the low baseline risk of CHD and limited discriminatory power, only 33% of all CHD events occurred in women classified as high risk. Conclusions: The FPS need recalibration for elderly men with better incorporation of the effect of age. In elderly women, FPS perform reasonably well. However, maintaining the rational of the high-risk threshold requires better performing models for a population with low incidence of CHD.

Clinical consequences of posttraumatic bone bruise in the knee (Article)

2007-06-01T00:00:00Z

Background: Bone bruise is often seen in posttraumatic knees, but the clinical relevance is unclear. Hypothesis: The presence of bone bruise is associated with increased pain severity in patients with sustained knee trauma. Study Design: Cohort study; Level of evidence, 2. Methods: We collected prospective data of 132 patients visiting their general practitioner after sustained knee trauma. Patients with bone bruise underwent a magnetic resonance imaging follow-up study that was discontinued when the bone bruise could no longer be discerned or after 1 year of follow-up. Bone bruise was assessed on magnetic resonance imaging, and pain severity was scored on a numeric rating scale (0-10) at baseline, and at 3, 6, and 12 months after trauma. The presence of bone bruise and pain severity (over time) were compared using linear regression analyses for repeated measurements. Adjustment was made for possible confounders: presence of meniscal tears, cruciate or collateral ligament ruptures, severe effusion, osteoarthritis, obesity, age, gender, work load, and sports load. Results: At baseline as well as during follow-up, bone bruise was associated with a slightly higher pain score. The differences, however, were very small (adjusted difference in pain severity 0.34 or less) and not statistically significant nor clinically relevant. Conclusion: There is no statistically significant relationship, nor a clinically relevant relationship, between the presence of bone bruise and pain severity in patients with sustained knee injury in general practice.

Diagnostic performance of the platelet function analyzer (PFA-100®) for the detection of disorders of primary haemostasis in patients with a bleeding history - A systematic review and meta-analysis (Article)

2007-06-01T00:00:00Z

The Platelet Function Analyzer (PFA-100®) is increasingly being used in the workup of patients with a bleeding diathesis. A profound knowledge of the possible diagnostic performance of this test is essential in order to make sound clinical decisions based on its results. It was the aim of this study to systematically review the published literature and provide valid estimates of the diagnostic performance of the PFA-100® for detecting disorders of primary haemostasis in newly presenting patients with a bleeding diathesis. A comprehensive literature search was performed for studies published between January 1994 and February 2006. Studies were eligible for the systematic review if they provided data supposed to be applicable to the determination of the diagnostic performance of the PFA-100®. Furthermore, they were included in a meta-analysis if study reporting allowed calculation of sensitivity and specificity and if study quality ensured minimized biases of these estimates for the described clinical setting. Pooled weighted sensitivity, specificity and diagnostic odds ratio were calculated applying random effects modelling and constructing summary operator characteristic curves. This was done separately for the available test modifications using either collagen/epinephrine (PFA-EPI) or collagen/adenosine-diphosphate (PFA-ADP) for platelet activation. Thirty-six articles were included in the systematic review. Six studies met our eligibility criteria for a meta-analysis. The major reason for exclusion from the meta-analysis was a case-control design. A total of 1486 and 1259 patients were included in the meta-analysis of the diagnostic performance of the PFA-EPI and PFA-ADP, respectively. Pooled weighted sensitivity and specificity of the PFA-EPI/PFA-ADP in detecting a disorder of primary haemostasis were: 82.5/66.9% (95%-confidence interval (95%-CI): 76.0-88.9%/57.9-75.9%), and 88.7/85.5% (95%-CI: 84.3-93.1%/82.0-89.1%). 83/75% of patients with a positive PFA-EPI/PFA-ADP result do have a disorder of primary haemostasis whereas 88/79% with a negative PFA-EPI/PFA-ADP result do not. The PFA-EPI appeared to have a higher sensitivity and better predictive values than the PFA-ADP in detecting disorders of primary haemostasis, although a rigorous gold standard definition for a disorder of primary haemostasis, particularly for platelet disorders, was not applied in most studies. The majority of the studies lacked important requirements for quality and reporting, precluding a more precise and definitive characterization of the clinical utility of the PFA-100®. This emphasizes the need for an evidence-based critical appraisal of diagnostic studies in haemostasis research in order to promote the conducting of studies that produce clinically relevant results.

Cost effectiveness of using computed tomography (CT) for minor head injury compared with several other management strategies (Letter To Editor)

2007-05-01T00:00:00Z

Letters to the editor [1] (Article)

2007-05-01T00:00:00Z

A history of loss of consciousness or post-traumatic amnesia in minor head injury: "conditio sine qua non" or one of the risk factors? (Article)

2007-04-01T00:00:00Z

OBJECTIVE: A history of loss of consciousness (LOC) or post-traumatic amnesia (PTA) is commonly considered a prerequisite for minor head injury (MHI), although neurocranial complications also occur when LOC/PTA are absent, particularly in the presence of other risk factors. The purpose of this study was to evaluate whether known risk factors for complications after MHI in the absence of LOC/PTA have the same predictive value as when LOC/PTA are present. METHODS: A prospective multicentre study was performed in four university hospitals between February 2002 and August 2004 of consecutive blunt head injury patients (> or = 16 years) presenting with a normal level of consciousness and a risk factor. Outcome measures were any neurocranial traumatic CT finding and neurosurgical intervention. Common odds ratios (OR) were estimated for each of the risk factors and tested for homogeneity. RESULTS: 2462 patients were included: 1708 with and 754 without LOC/PTA. Neurocranial traumatic findings on CT were present in 7.5% and were more common when LOC/PTA was present (8.7%). Neurosurgical intervention was required in 0.4%, irrespective of the presence of LOC/PTA. ORs were comparable across the two subgroups (p>0.05), except for clinical evidence of a skull fracture, with high ORs both when LOC/PTA was present (OR = 37, 95% CI 17 to 80) or absent (OR = 6.9, 95% CI 1.8 to 27). LOC and PTA had significant ORs of 1.9 (95% CI 1.0 to 2.7) and 1.7 (95% CI 1.3 to 2.3), respectively. CONCLUSION: Known risk factors have comparable ORs in MHI patients with or without LOC or PTA. MHI patients without LOC or PTA need to be explicitly considered in clinical guidelines.

MRI for Traumatic Knee Injury: A Review (Article)

2007-04-01T00:00:00Z

Magnetic resonance imaging (MRI) is a well-established technique for detecting internal derangements of the knee joint with high diagnostic accuracy. It is an effective tool to select patients for targeted therapeutic arthroscopy. In this article, indications for knee MRI and most commonly used MRI techniques are outlined, followed by an overview of the most frequently encountered traumatic knee derangements in daily practice and their appearance and grading system on MRI. Lesions discussed include fractures, osteochondral lesions, bone bruise, cruciate and collateral ligament lesions, and meniscal tears. Finally, common pitfalls and recent developments in knee MRI are addressed.

Predicting Intracranial Traumatic Findings on Computed Tomography in Patients with Minor Head Injury: The CHIP Prediction Rule (Article)

2007-03-01T00:00:00Z

Abstract BACKGROUND: Prediction rules for patients with minor head injury suggest that the use of computed tomography (CT) may be limited to certain patients at risk for intracranial complications. These rules apply only to patients with a history of loss of consciousness, which is frequently absent. OBJECTIVE: To develop a prediction rule for the use of CT in patients with minor head injury, regardless of the presence or absence of a history of loss of consciousness. DESIGN: Prospective, observational study. SETTING: 4 university hospitals in the Netherlands that participated in the CT in Head Injury Patients (CHIP) study. PATIENTS: Consecutive adult patients with minor head injury (> or =16 years of age) with a Glasgow Coma Scale (GCS) score of 13 to 14 or with a GCS score of 15 and at least 1 risk factor. MEASUREMENTS: Outcomes were any intracranial traumatic CT finding and neurosurgical intervention. The authors performed logistic regression analysis by using variables from existing prediction rules and guidelines, with internal validation by using bootstrapping. RESULTS: 3181 patients were included (February 2002 to August 2004): 243 (7.6%) had intracranial traumatic CT findings and 17 (0.5%) underwent neurosurgical intervention. A detailed prediction rule was developed from which a simple rule was derived. Sensitivity of both rules was 100% for neurosurgical interventions, with an associated specificity of 23% to 30%. For intracranial traumatic CT findings, sensitivity and specificity were 94% to 96% and 25% to 32%, respectively. Potential CT reduction by implementing the prediction rule was 23% to 30%. Internal validation showed slight optimism for the model's performance. LIMITATION: External validation of the prediction model will be required. CONCLUSION: The authors propose the highly sensitive CHIP prediction rule for the selective use of CT in patients with minor head injury with or without loss of consciousness.

Limitations of acceptability curves for presenting uncertainty in cost-effectiveness analysis (Article)

2007-03-01T00:00:00Z

Clinical journals increasingly illustrate uncertainty about the cost and effect of health care interventions using cost-effectiveness acceptability curves (CEACs). CEACs present the probability that each competing alternative is optimal for a range of values of the cost-effectiveness threshold. The objective of this article is to demonstrate the limitations of CEACs for presenting uncertainty in cost-effectiveness analyses. These limitations arise because the CEAC is unable to distinguish dramatically different joint distributions of incremental cost and effect. A CEAC is not sensitive to any change of the incremental joint distribution in the upper left and lower right quadrants of the cost-effectiveness plane; neither is it sensitive to radial shift of the incremental joint distribution in the upper right and lower left quadrants. As a result, CEACs are ambiguous to risk-averse policy makers, inhibit integration with risk attitude, hamper synthesis with other evidence or opinions, and are unhelpful to assess the need for more research. Moreover, CEACs may mislead policy makers and can incorrectly suggest medical importance. Both for guiding immediate decisions and for prioritizing future research, these considerable drawbacks of CEACs should make us rethink their use in communicating uncertainty. As opposed to CEACs, confidence and credible intervals do not conflate magnitude and precision of the net benefit of health care interventions. Therefore, they allow (in)formal synthesis of study results with risk attitude and other evidence or opinions. Presenting the value of information in addition to these intervals allows policy makers to evaluate the need for more empirical research.

Impact of Claudication and Its Treatment on Quality of Life (Article)

2007-03-01T00:00:00Z

Improvement in quality of life is the ultimate goal of healthcare for the treatment of intermittent claudication. Until recently, the measures of success after therapy were those derived from the vascular laboratory, including ankle-brachial indices and ankle and toe pressures. There are now several validated and reliable survey tools that can assess patient-reported quality of life in a generic or disease-specific manner. Major survey instruments are reviewed. The information gathered through these quality-of-life assessment tools is important to all those involved in the care of patients with peripheral arterial disease. Although claudication is neither life- nor limb-threatening, it has a significant negative impact on quality of life, as measured by these instruments. Patients so afflicted report more bodily pain, worse physical function, and worse perceived health, in addition to limited walking ability. These measures of quality of life do not correlate with standard parameters of ankle-brachial index or ankle pressures. Treatment of the claudicant with exercise therapy and percutaneous or open revascularization also impacts quality of life. Each of these modalities is capable of improving quality of life, but some are associated with decline over time. The major benefits and risks to quality of life of these specific forms of treatment for the claudicant are reviewed. This data demonstrates that patients suffering from symptoms of intermittent claudication are best served by therapies that address their major self-reported impediments to quality of life.

Comparison of hemodialysis and peritoneal dialysis survival in The Netherlands (Article)

2007-01-01T00:00:00Z

Considerable geographic variation exists in the relative use of hemodialysis (HD) vs peritoneal dialysis (PD). Studies comparing survival between these modalities have yielded conflicting results. Our aim was to compare the survival of Dutch HD and PD patients. We developed Cox regression models using 16 643 patients from the Dutch End-Stage Renal Disease Registry (RENINE) adjusting for age, gender, primary renal disease, center of dialysis, year of start of renal replacement therapy, and included several interaction terms. We assumed definite treatment assignment at day 91 and performed an intention-to-treat analysis, censoring for transplantation. To account for time dependency, we stratified the analysis into three time periods, >3-6, >6-15, and >15 months. For the first period, the mortality hazard ratio (HR) of PD compared with HD patients was 0.26 (95% confidence interval (CI) 0.17-0.41) for 40-year-old non-diabetics, which increased with age and presence of diabetes to 0.95 (95% CI 0.64-1.39) for 70-year-old patients with diabetes as primary renal disease. The HRs of the second period were generally higher. After 15 months, the HR was 0.86 (95% CI 0.74-1.00) for 40-year-old non-diabetics and 1.42 (95% CI 1.23-1.65) for 70-year-old patients with diabetes as primary renal disease. We conclude that the survival advantage for Dutch PD compared with HD patients decreases over time, with age and in the presence of diabetes as primary disease.

CT scanning for minor head injury (Letter To Editor)

2006-02-01T00:00:00Z

Diagnostic performance of duplex ultrasound in patients suspected of carotid artery disease: the ipsilateral versus contralateral artery. (Article)

2005-10-01T00:00:00Z

BACKGROUND AND PURPOSE: To evaluate duplex ultrasonographic thresholds for the determination of 70% to 99% stenosis of the ipsilateral and contralateral internal carotid artery in patients with symptoms of amaurosis fugax, transient ischemic attack (TIA), or minor stroke based on 2 criteria: maximizing accuracy and optimizing cost-effectiveness and to compare these with current recommendations. METHODS: From January 1997 to January 2000, a prospective multicenter study was conducted including 350 consecutive patients with symptoms of amaurosis fugax, TIA, or minor stroke who underwent bilateral duplex ultrasonography and digital subtraction angiography. A linear regression analysis was performed to estimate the degree of angiographic stenosis as a function of the peak systolic velocity (PSV). PSV thresholds were calculated for the ipsilateral and contralateral carotid arteries based on maximizing accuracy and optimizing cost-effectiveness. RESULTS: The PSV measurements significantly overestimated the angiographic stenosis in the contralateral artery (9.5%; 95% CI, 6.3% to 12.7%) compared with the ipsilateral carotid artery. The recommended PSV threshold for the diagnosis of 70% to 99% stenosis is 230 cm/s. Maximizing accuracy, the optimal PSV threshold for the ipsilateral artery was 280 cm/s, and for the contralateral artery, 370 cm/s for diagnosing a 70% to 99% stenosis. Optimizing cost-effectiveness, the optimal PSV threshold was 220 cm/s for ipsilateral and 290 cm/s for contralateral carotid arteries. CONCLUSIONS: PSV measurements overestimate the degree of angiographic stenosis in the contralateral carotid artery in patients with symptoms of amaurosis fugax, TIA, or minor stroke. Separate PSV thresholds should be used for the ipsilateral and contralateral carotid artery. PSV thresholds that optimize cost-effectiveness differ from the recommended thresholds and from thresholds that maximize accuracy.

External validation of the Canadian CT Head Rule and the New Orleans Criteria for CT scanning in patients with minor head injury. (Article)

2005-09-28T00:00:00Z

CONTEXT: Two decision rules for indications of computed tomography (CT) in patients with minor head injury, the Canadian CT Head Rule (CCHR) and the New Orleans Criteria (NOC), suggest that CT scanning may be restricted to patients with certain risk factors, which would lead to important reductions in the use of CT scans. OBJECTIVE: To validate and compare these 2 published decision rules in Dutch patients with head injuries. DESIGN, SETTING, AND PATIENTS: A prospective multicenter study conducted between February 11, 2002, and August 31, 2004, in 4 university hospitals in the Netherlands of 3181 consecutive adult patients with minor head injury who presented with a Glasgow Coma Scale (GCS) score of 13 to 14 or with a GCS score of 15 and at least 1 risk factor. MAIN OUTCOME MEASURES: Primary outcome was any neurocranial traumatic finding on CT scan. Secondary outcomes were neurosurgical intervention and clinically important CT findings. Sensitivity and specificity were estimated for each outcome for the CCHR and the NOC, using both rules as originally derived and also as adapted to apply to an expanded patient population. RESULTS: Of 3181 patients with a GCS score of 13 to 15, neurosurgical intervention was performed in 17 patients (0.5%); neurocranial traumatic CT findings were present in 312 patients (9.8%). Sensitivity for neurosurgical intervention was 100% for both the CCHR and the NOC. The NOC had a higher sensitivity for neurocranial traumatic findings and for clinically important findings (97.7%-99.4%) than did the CCHR (83.4%-87.2%). Specificities were very low for the NOC (3.0%-5.6%) and higher for the CCHR (37.2%-39.7%). The estimated potential reduction in CT scans for patients with minor head injury would be 3.0% for the adapted NOC and 37.3% for the adapted CCHR. CONCLUSIONS: For patients with minor head injury and a GCS score of 13 to 15, the CCHR has a lower sensitivity than the NOC for neurocranial traumatic or clinically important CT findings, but would identify all cases requiring neurosurgical intervention, and has greater potential for reducing the use of CT scans.

Imaging peripheral arterial disease: a randomized controlled trial comparing contrast-enhanced MR angiography and multi-detector row CT angiography. (Article)

2005-09-01T00:00:00Z

PURPOSE: To prospectively evaluate clinical utility, patient outcomes, and costs of contrast material-enhanced magnetic resonance (MR) angiography compared with multi-detector row computed tomographic (CT) angiography for initial imaging in the diagnostic work-up of patients with peripheral arterial disease. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Patients referred for diagnostic imaging work-up to evaluate the feasibility of a revascularization procedure were randomly assigned to undergo either MR angiography or CT angiography. Clinical utility was assessed with therapeutic confidence (scale of 0-10) at initial imaging and with the need for additional imaging. Patient outcomes included ankle-brachial index, maximum walking distance, change in clinical status, and health-related quality of life. Actual diagnostic and therapeutic costs were calculated from the hospital perspective. Differences between group means were calculated with unpaired t tests and 95% confidence intervals. RESULTS: A total of 157 consecutive patients with peripheral arterial disease were prospectively randomized to undergo MR angiography (51 men, 27 women; mean age, 63 years) or CT angiography (50 men, 29 women; mean age, 64 years). For one of the 78 patients in the MR group, no data were available. Mean confidence for MR angiography (7.7) was slightly lower than that for CT angiography (8.0, P = .8). During 6 months of follow-up, 13 patients in the MR group compared with 10 patients in the CT group underwent additional vascular imaging (P = .5). Although not statistically significant, there was a consistent trend of less improvement in the MR group across all patient outcomes. The average cost for diagnostic imaging was 359 ($438) higher in the MR group than in the CT group (95% confidence interval: 209, 511 [$255, $623]; P < .001). Therapeutic costs were higher in the MR group, but the difference was not significant. CONCLUSION: The results suggest that CT angiography has some advantages over MR angiography in the initial evaluation of peripheral arterial disease.

Acute peripheral joint injury: cost and effectiveness of low-field- strength MR imaging--results of randomized controlled trial. (Article)

2005-09-01T00:00:00Z

PURPOSE: To assess prospectively if a short imaging examination performed with low-field-strength dedicated magnetic resonance (MR) imaging in addition to radiography is effective and cost saving compared with the current diagnostic imaging strategy (radiography alone) in patients with recent acute traumatic injury of the wrist, knee, or ankle. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. Patients with recent trauma of the wrist, knee, or ankle were randomized across two diagnostic strategies: radiography alone (reference group) or radiography followed by a short MR imaging examination (intervention group). Measures of effectiveness included the number of additional diagnostic procedures, time to last diagnostic procedure, and number of days absent from work. Measures of effectiveness were analyzed by using an exact Wilcoxon-Mann-Whitney test. Time to convalescence and quality of life were analyzed by using a t test. Cost analysis was performed from a societal perspective and analyzed by using a t test. RESULTS: Five hundred patients (207 women, 293 men; mean age, 34.8 years) with acute injury of the wrist, knee, or ankle were randomized. In the intervention group, quality of life for patients with knee injuries was significantly higher during the first 6 weeks, and time to completion of diagnostic work-up was significantly shorter (mean, 3.5 days for intervention group vs 17.3 days for reference group). The number of additional diagnostic procedures was significantly lower in the intervention group versus the reference group (nine vs 35, respectively) for patients with knee injuries. Patients with knee injuries showed the largest difference in costs (intervention group, 1820 [$1966]; reference group, 2231 [$2409]) owing to a reduction in productivity loss. Costs were higher in patients with wrist injuries and almost equal in patients with ankle injuries. All cost differences, however, were not significant. CONCLUSION: Compared with radiography, MR imaging in patients with acute wrist or ankle injuries is neither cost saving nor effective in expediting diagnostic work-up or improving quality of life. In patients with knee injuries, a short MR imaging examination shortens the time to completion of diagnostic work-up, reduces the number of additional diagnostic procedures, improves quality of life in the first 6 weeks, and may reduce costs associated with lost productivity.

Intermittent claudication: functional capacity and quality of life after exercise training or percutaneous transluminal angioplasty--systematic review. (Article)

2005-06-01T00:00:00Z

PURPOSE: To systematically review published data about the short- and long-term effects of exercise training and angioplasty on functional capacity and quality of life of patients with intermittent claudication. MATERIALS AND METHODS: Articles published between January 1980 and February 2003 were included if patients had intermittent claudication treated with exercise training or angioplasty and if both functional capacity and quality-of-life scores from Medical Outcomes Study 36-Item Short Form health survey were reported for at least 3 months of follow-up. Data were pooled by using a random effects model and weighted means. Pooled results were compared between the treatment groups by using the chi2 test and the Student t test (alpha = .05, two sided). RESULTS: In the analyses, five studies (202 patients) were included in the exercise group, and three studies (470 patients), in the angioplasty group. At 3 months of follow-up, the ankle-brachial index was significantly improved in the angioplasty group (mean change, 0.18; P < .01) but not in the exercise group (mean change, 0.01; P = .29). At 3 months, quality of life was significantly improved with regard to ratings of physical functioning and bodily pain in the exercise group (mean change, 18 and 10, respectively; P < .01) and physical role functioning in the angioplasty group (mean change, 30; P = .03). Mean change in ankle-brachial index significantly differed between the two treatment groups at 3 and 6 months (P < .01); mean change in quality-of-life scores did not. CONCLUSION: Improvement in quality of life was demonstrated after both exercise training and angioplasty, whereas functional capacity showed significant improvement after angioplasty. The ankle-brachial index significantly differed between the two treatment groups at 3 and 6 months, whereas the quality-of-life scores did not.

Decision making in the face of uncertainty and resource constraints: examples from trauma imaging. (Article)

2005-05-01T00:00:00Z

The purpose of this review is to illustrate how tools and concepts from decision and cost-effectiveness analyses can be used to help make decisions in the face of uncertainty and resource constraints, select appropriate subjects for imaging, choose between competing imaging modalities, and prioritize future research. Examples from trauma imaging illustrate the use of the presented tools. The author advocates the PROACTIVE approach in deciding which imaging strategies are cost-effective (PRO for defining the problem, reframing the problem from multiple perspectives, and focusing on the objective; ACT for expanding the alternatives, considering the consequences and associated chances of each alternative, and identifying the trade-offs involved; IVE for integrating the evidence and values, optimizing the value of interest, and exploring uncertainty). Simulation models play an important role in the assessment of imaging strategies by helping to identify alternative strategies and to integrate the best-available evidence related to risks, benefits, patient values, and costs. Exploring the uncertainty in the evidence and assessing the value of obtaining more information can help prioritize future research and guide study design.

Acute wrist trauma: value of a short dedicated extremity MR imaging examination in prediction of need for treatment (Article)

2005-01-01T00:00:00Z

PURPOSE: To assess predictive value of a short magnetic resonance (MR) imaging examination in addition to or instead of radiography in patients with acute wrist trauma to identify patients who require additional treatment versus those who do not and can be discharged without further follow-up. MATERIALS AND METHODS: Informed consent was obtained from all participating patients; the institutional review board approved the randomized controlled trial and use of data to create prediction models. Of 90 patients (37 female, 53 male; mean age, 40.0 years), 87 with acute wrist trauma were randomized to undergo radiography (n = 43) or radiography and a short MR imaging examination with low-field-strength dedicated extremity MR system (n = 44). Age, sex, trauma mechanism, presence of tenderness of the anatomic snuffbox, radiographic results, MR imaging results, and treatment data were collected. Univariable and multivariable logistic regression analysis was used to create four models for prediction of treatment need. RESULTS: Thirty-six patients had one or more fractures; one patient had a marked soft-tissue lesion. In univariable analysis, age (odds ratio, 1.02; 95% confidence interval: 1.00, 1.05), anatomic snuffbox tenderness (odds ratio, 2.31; 95% confidence interval: 0.90, 5.96), radiographic results (odds ratio, 31.2; 95% confidence interval: 8.90, 109), and positive MR imaging results versus MR imaging not performed (odds ratio, 1.86; 95% confidence interval: 0.57, 6.06) were significantly predictive of treatment need. In multivariable analysis, radiographic results (odds ratio, 24.7; 95% confidence interval: 6.59, 93.1) and positive MR imaging results (odds ratio, 6.28; 95% confidence interval: 1.27, 31.0) were significantly predictive of treatment need. Negative MR imaging results were not significantly predictive (odds ratio, 0.87; 95% confidence interval: 0.20, 3.82). CONCLUSION: A short MR imaging examination with a low-field-strength MR imaging system following radiography in initial evaluation of patients with acute wrist trauma has additional value in prediction of treatment need; it does not have value in identification of patients who can be discharged without further follow-up.

Acute knee trauma: value of a short dedicated extremity MR imaging examination for prediction of subsequent treatment (Article)

2005-01-01T00:00:00Z

PURPOSE: To assess the predictive value of a short magnetic resonance (MR) imaging examination, in addition to or instead of radiography, performed in patients with acute knee trauma to identify those who require additional treatment versus those who do not and can be discharged without further follow-up. MATERIALS AND METHODS: The randomized controlled trial and use of collected data for prediction modeling were approved by the institutional review board; informed consent was obtained. Patients with recent knee injury were included in the trial if radiography was ordered. They were randomized into a group undergoing only radiography and a group undergoing radiography plus immediate MR imaging. A 0.2-T dedicated extremity MR imager and four short pulse sequences were used. Univariable and multivariable logistic regression analysis was used to evaluate patient characteristics, trauma mechanism, and findings at radiography and MR imaging for their value in prediction of need for subsequent treatment within the 6-month follow-up. RESULTS: Data in 189 patients (123 male patients, 66 female patients; mean age, 33.4 years), 109 of whom underwent treatment after their initial visit, were analyzed. Age of 30 years or older, indirect trauma mechanism, radiographic results, and MR imaging results were significant predictors of need for treatment in univariable and multivariable analyses (P < .05). In the multivariable analysis, only abnormal MR imaging results were significantly predictive of need for treatment, and only when MR imaging replaced radiography (odds ratio, 2.61; 95% confidence interval: 1.12, 6.06). CONCLUSION: Implementation of a dedicated extremity MR imaging examination, in addition to or instead of radiography, performed in patients with traumatic knee injury improves prediction of the need for additional treatment but does not significantly aid in identification of patients who can be discharged without further follow-up. Value of a short MR imaging examination in the initial stage after knee trauma is limited.

Acute ankle trauma: value of a short dedicated extremity MR imaging examination in prediction of need for treatment (Article)

2005-01-01T00:00:00Z

PURPOSE: To assess predictive value of a short magnetic resonance (MR) imaging examination with or instead of radiography performed in patients with acute ankle trauma to identify those who require additional treatment versus those who do not and can be discharged without further follow-up. MATERIALS AND METHODS: Informed consent was obtained from all participating patients, and the institutional review board approved the randomized controlled trial and use of data to create prediction models. In a prospective controlled trial, 197 patients with recent ankle trauma (92 women, 105 men) were randomized into two groups: those who underwent radiography and those who underwent a combination of radiography and MR imaging. Data about side of injury, trauma mechanism, and results of radiography and MR imaging were collected. Additional treatment was necessary in 109 of 197 patients after their initial hospital visit. With univariable and multivariable regression analysis, four models were created for prediction of treatment. RESULTS: In univariable analysis, age (odds ratio [OR], 1.02; 95% confidence interval: 1.00, 1.04), radiographic results (OR, 7.92; 95% confidence interval: 3.17, 19.8), and positive or uncertain results in patients who underwent MR imaging versus patients who did not (OR, 2.42; 95% confidence interval: 1.25, 4.70) were predictive of treatment. In the multivariable analysis, positive or uncertain MR imaging results (OR, 2.61; 95% confidence interval: 1.28, 5.30) contributed significantly to prediction of subsequent treatment. Negative MR imaging results did not contribute significantly (OR, 0.66; 95% confidence interval: 0.27, 1.61). CONCLUSION: A limited MR imaging examination in initial evaluation of acute ankle injury with radiography has additional predictive value in identification of patients who need treatment but does not add significant information in identification of those who can be discharged without further follow-up. A limited MR imaging examination cannot replace radiography for prediction of need for additional treatment.

Peripheral arterial disease: therapeutic confidence of CT versus digital subtraction angiography and effects on additional imaging recommendations. (Article)

2004-11-01T00:00:00Z

PURPOSE: To compare multi-detector row computed tomographic (CT) angiography and digital subtraction angiography (DSA) prior to revascularization in patients with symptomatic peripheral arterial disease for the purpose of assessing recommendations for additional imaging and physician confidence ratings for chosen therapy. MATERIALS AND METHODS: In a randomized controlled trial, 73 patients were assigned to CT angiography, and 72 were assigned to DSA. Physician confidence in the treatment decision was measured as a continuous outcome on a scale of 0-10 (uncertain to certain) and as a dichotomous outcome (further imaging recommended, yes or no). Mean confidence scores and additional imaging recommendations were compared between CT and DSA groups in an intention-to-diagnose-and-treat analysis. To detect trends in confidence, confidence scores were plotted over time, and multiple linear regression analysis was performed. To detect trends in additional imaging recommendations, logistic regression analysis was used. Data from eligible nonrandomized patients were analyzed separately. RESULTS: No statistically significant difference in baseline characteristics between randomized groups was found. CT had a lower confidence score than did DSA (7.2 vs 8.2, P < .001). Further imaging was recommended more often after CT (25 of 71 patients, 35%) than after DSA (nine of 66 patients, 14%; P = .003). Analysis of trends demonstrated increasing (but not statistically significant) confidence in CT and stable confidence in DSA. No significant difference was found in baseline characteristics between randomized and nonrandomized patients. Among nonrandomized patients, no significant difference in mean confidence score (8.2 vs 8.3, P = .26) was found between CT (n = 24) and DSA (n = 26). CONCLUSION: With CT angiography, physician confidence decreases with an associated increase in additional imaging prior to revascularization in patients with symptomatic peripheral arterial disease. Given that CT is less invasive than DSA, results suggest that CT may replace DSA in selected cases.

Cost-effectiveness targets for multi-detector row CT angiography in the work-up of patients with intermittent claudication. (Article)

2003-06-01T00:00:00Z

PURPOSE: To determine the costs, sensitivity for detection of significant stenoses, and proportion of equivocal multi-detector row computed tomographic (CT) angiography results in the work-up of patients with intermittent claudication that would make this imaging examination cost-effective compared with gadolinium-enhanced magnetic resonance (MR) angiography. MATERIALS AND METHODS: A decision model was used to compare the societal cost-effectiveness of a new imaging modality with that of gadolinium-enhanced MR angiography. Main outcome measures were quality-adjusted life years (QALYs) and lifetime costs. By using threshold analysis of a given willingness to pay per QALY, target values for costs, sensitivity for detection of significant stenoses, and proportion of cases requiring additional work-up with intraarterial digital subtraction angiography owing to equivocal results of the new modality were determined. The base case evaluated was that of 60-year-old men with severe intermittent claudication and assumed an incremental cost-effectiveness threshold of 100,000 US dollars per QALY. RESULTS: If treatment were limited to angioplasty, a new imaging modality would be cost-effective if the costs were 300 US dollars and the sensitivity was 85%, even if up to 35% of patients needed additional work-up. When both angioplasty and bypass surgery were considered as treatment options, a new imaging modality was cost-effective if the costs were 300 US dollars, the sensitivity was higher than 94%, and 20% of patients required additional work-up. CONCLUSION: Multi-detector row CT angiography, as compared with currently used imaging modalities such as MR angiography, has the potential to be cost-effective in the evaluation of patients with intermittent claudication.

MR imaging of the menisci and cruciate ligaments: a systematic review. (Article)

2003-03-01T00:00:00Z

PURPOSE: To systematically review and synthesize published data on the diagnostic performance of magnetic resonance (MR) imaging of the menisci and cruciate ligaments and to assess the effect of study design characteristics and magnetic field strength on diagnostic performance. MATERIALS AND METHODS: Articles published between 1991 and 2000 were included if at least 30 patients were studied, arthroscopy was the reference standard, the magnetic field strength was reported, positivity criteria were defined, and the absolute numbers of true-positive, false-negative, true-negative, and false-positive results were available or derivable. Pooled weighted and summary receiver operating characteristic (ROC) analyses were performed for tears of both menisci and both cruciate ligaments separately and for the four lesions combined, by using random effects models. Differences were assessed according to lesion type. RESULTS: Twenty-nine of 120 retrieved articles were included. Pooled weighted sensitivity was higher for medial meniscal tears than that for lateral meniscal tears. However, pooled weighted specificity for the medial meniscus was lower than that for the lateral meniscus. In summary ROC analyses performed per lesion, various study design characteristics were found to influence diagnostic performance. Higher magnetic field strength significantly improved discriminatory power only for anterior cruciate ligament tears. When all lesions were combined in one overall summary ROC analysis, magnetic field strength was a significant but modest predictor of diagnostic performance. CONCLUSION: Diagnostic performance of MR imaging of the knee is different according to lesion type and is influenced by various study design characteristics. Higher magnetic field strength modestly improves diagnostic performance, but a significant effect was demonstrated only for anterior cruciate ligament tears.

Living renal donors: optimizing the imaging strategy--decision- and cost-effectiveness analysis (Article)

2003-01-01T00:00:00Z

PURPOSE: To determine the most cost-effective strategy for preoperative imaging performed in potential living renal donors. MATERIALS AND METHODS: In a decision-analytic model, the societal cost-effectiveness of digital subtraction angiography (DSA), gadolinium-enhanced magnetic resonance (MR) angiography, contrast material-enhanced spiral computed tomographic (CT) angiography, and combinations of these imaging techniques was evaluated. Outcome measures included lifetime cost, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios. A base-case analysis was performed with a 40-year-old female donor and a 40-year-old female recipient. RESULTS: For the donor, MR angiography (24.05 QALYs and 9,000 dollars) dominated all strategies except for MR angiography with CT angiography, which had an incremental ratio of 245,000 dollars per QALY. For the recipient, DSA and DSA with MR angiography yielded similar results (10.46 QALYs and 179,000 dollars) and dominated all other strategies. When results for donor and recipient were combined, DSA dominated all other strategies (34.51 QALYs and 188,000 dollars). If DSA was associated with a 99% specificity or less for detection of renal disease, MR angiography with CT angiography was superior (34.47 QALYs and 190,000 dollars). CONCLUSION: For preoperative imaging in a potential renal donor, DSA is the most cost-effective strategy if it has a specificity greater than 99% for detection of renal disease; otherwise, MR angiography with CT angiography is the most cost-effective strategy.

MR imaging: a 'One Stop Shop' Modality for Preoperative Evaluation of Potential Living Kidney-Donors (Article)

2003-01-01T00:00:00Z

At many institutions, magnetic resonance (MR) angiography is the technique of choice for assessment of the renal arteries and renal parenchyma in potential living kidney donors. The renal arteries and renal veins have a varied anatomy and may consist of one or more vessels at several levels with variable calibers and levels of branching. These findings may play an important role in the surgeon's decision about which kidney to harvest, especially if laparoscopic nephrectomy is used. A comprehensive MR imaging protocol is used at one hospital to assess the arteries, veins, parenchyma, and collecting system of the kidneys. The protocol includes T2-weighted single-shot fast spin-echo imaging, fat-saturated T2-weighted fast spin-echo imaging, three-dimensional MR angiography and MR venography, and delayed fat-saturated three-dimensional T1-weighted gradient-echo imaging. Meticulous assessment of the source images as well as images produced with various postprocessing methods, such as full maximum intensity projection, targeted maximum intensity projection, and axial and oblique reformation, allows detailed description of the vascular anatomy and its relationship to the collecting system and parenchyma to facilitate the surgeon's decision making. The findings of MR imaging are comparable with those of other imaging modalities.

A meta-analysis comparing the prognostic accuracy of six diagnostic tests for predicting perioperative cardiac risk in patients undergoing major vascular surgery (Article)

2003-01-01T00:00:00Z

OBJECTIVE: To evaluate the discriminatory value and compare the predictive performance of six non-invasive tests used for perioperative cardiac risk stratification in patients undergoing major vascular surgery. DESIGN: Meta-analysis of published reports. METHODS: Eight studies on ambulatory electrocardiography, seven on exercise electrocardiography, eight on radionuclide ventriculography, 23 on myocardial perfusion scintigraphy, eight on dobutamine stress echocardiography, and four on dipyridamole stress echocardiography were selected, using a systematic review of published reports on preoperative non-invasive tests from the Medline database (January 1975 and April 2001). Random effects models were used to calculate weighted sensitivity and specificity from the published results. Summary receiver operating characteristic (SROC) curve analysis was used to evaluate and compare the prognostic accuracy of each test. The relative diagnostic odds ratio was used to study the differences in diagnostic performance of the tests. RESULTS: In all, 8119 patients participated in the studies selected. Dobutamine stress echocardiography had the highest weighted sensitivity of 85% (95% confidence interval (CI) 74% to 97%) and a reasonable specificity of 70% (95% CI 62% to 79%) for predicting perioperative cardiac death and non-fatal myocardial infarction. On SROC analysis, there was a trend for dobutamine stress echocardiography to perform better than the other tests, but this only reached significance against myocardial perfusion scintigraphy (relative diagnostic odds ratio 5.5, 95% CI 2.0 to 14.9). CONCLUSIONS: On meta-analysis of six non-invasive tests, dobutamine stress echocardiography showed a positive trend towards better diagnostic performance than the other tests, but this was only significant in the comparison with myocardial perfusion scintigraphy. However, dobutamine stress echocardiography may be the favoured test in situations where there is valvar or left ventricular dysfunction.

CT screening: a trade-off of risks, benefits, and costs (Article)

2003-01-01T00:00:00Z

Study design for concurrent development, assessment, and implementation of new diagnostic imaging technology (Article)

2002-01-01T00:00:00Z

With current constraints on health care resources and emphasis on value for money, new diagnostic imaging technologies must be assessed and their value demonstrated. The state of the art in the field of diagnostic imaging technology assessment advocates a hierarchical step-by-step approach. Although rigorous, such a hierarchical assessment is time-consuming, and, given the current rapid advances in technology, results are often too late to influence management and policy decisions. The purpose of this article is to discuss a study design in which development, assessment, and implementation of new diagnostic imaging technology take place concurrently in one integrated process. An empirically based pragmatic study design is proposed for imaging technology assessment. To minimize bias and enable comparison with current technology, a randomized controlled design is used whenever feasible and ethical. Outcome measures should reflect the clinical decision-making process based on imaging information and acceptance of the new test. Outcome measures can include additional imaging studies requested, costs of diagnostic work-up and treatment, physicians' confidence in therapeutic decision making, recruitment rate, and patient outcome measures related to the clinical problem. The key feature of the proposed study design is analysis of trends in outcome measures over time.

Cost and patency rate targets for the development of endovascular devices to treat femoropopliteal arterial disease (Article)

2001-01-01T00:00:00Z

PURPOSE: To determine the criteria that would make use of an endovascular device cost-effective compared with bypass surgery and percutaneous transluminal angioplasty in the treatment of femoropopliteal arterial disease. MATERIALS AND METHODS: A decision model was developed to compare treatment with the use of a hypothetical endovascular device with established therapies. Cost-effectiveness from the perspective of the health care system was considered. Outcome measures were lifetime costs and quality-adjusted life-years. With the use of net health benefit calculations and threshold analysis, combinations of costs and patency rates were determined that would make the device cost-effective compared with established therapies. In subgroup and sensitivity analyses, the effect on decision-making of sex, age, indication, lesion type, procedural risk, and society's willingness to pay for incremental gain in health were explored. RESULTS: Use of a device that costs $3,000 would be cost-effective compared with bypass surgery for critical ischemia if the 5-year patency rate is 29%-46%. Use of the same device would be cost-effective compared with angioplasty for disabling claudication and stenosis if the 5-year patency rate is 69%-86%. CONCLUSION: The target combinations of costs and patency rates found in this study are probably attainable, and further development of such endovascular devices seems warranted.

Balloon dilation and stent implantation for treatment of femoropopliteal arterial disease: meta-analysis (Article)

2001-01-01T00:00:00Z

PURPOSE: To perform a meta-analysis of long-term results of balloon dilation and stent implantation in the treatment of femoropopliteal arterial disease. MATERIALS AND METHODS: The English-language literature was searched for studies published between 1993 and 2000. Inclusion criteria for articles were presentation of long-term primary patency rates, standard errors (explicitly reported or derivable), and baseline characteristics of the study population. Two reviewers independently extracted data, and discrepancies were resolved by consensus. Primary patency rates were combined by using a technique that allows adjustment for differences across study populations. Analyses were adjusted for lesion type and clinical indication. RESULTS: Nineteen studies met the inclusion criteria, representing 923 balloon dilations and 473 stent implantations. Combined 3-year patency rates after balloon dilation were 61% (standard error, 2.2%) for stenoses and claudication, 48% (standard error, 3.3%) for occlusions and claudication, 43% (standard error, 4.1%) for stenoses and critical ischemia, and 30% (standard error, 3.7%) for occlusions and critical ischemia. The 3-year patency rates after stent implantation were 63%-66% (standard error, 4.1%) and were independent of clinical indication and lesion type. Funnel plots demonstrated an asymmetric distribution of the data points associated with stent studies. CONCLUSION: Balloon dilation and stent implantation for claudication and stenosis yield similar long-term patency rates. For more severe femoropopliteal disease, the results of stent implantation seem more favorable. Publication bias could not be ruled out.

Peripheral arterial disease: gadolinium-enhanced MR angiography versus color-guided duplex US--a meta-analysis (Article)

2000-01-01T00:00:00Z

PURPOSE: To summarize and compare the published data on gadolinium-enhanced magnetic resonance (MR) angiography and color-guided duplex ultrasonography (US) for the work-up for peripheral arterial disease. MATERIALS AND METHODS: Studies published between January 1984 and November 1998 were included if (a) gadolinium-enhanced MR angiography and/or color-guided duplex US were performed for evaluation of arterial stenoses and occlusions in the work-up for peripheral arterial disease of the lower extremities, (b) conventional angiography was the reference standard, and (c) absolute numbers of true-positive, false-negative, true-negative, and false-positive results were available or derivable. RESULTS: With a random effects model, pooled sensitivity for MR angiography (97.5% [95% CI: 95.7%, 99.3%]) was higher than that for duplex US (87.6% [95% CI: 84.4%, 90.8%]). Pooled specificities were similar: 96.2% (95% CI: 94.4%, 97.9%) for MR angiography and 94.7% (95% CI: 93.2%, 96.2%) for duplex US. Summary receiver operating characteristic analysis demonstrated better discriminatory power for MR angiography than for duplex US. Regression coefficients for MR angiography versus US were 1.67 (95% CI: -0.23, 3.56) with adjustment for covariates, 2.11 (95% CI: 0.12, 4.09) without such adjustment, and 1.73 (95% CI: 0.44, 3.02) with a random effects model. CONCLUSION: Gadolinium-enhanced MR angiography has better discriminatory power than does color-guided duplex US and is a highly sensitive and specific method, as compared with conventional angiography, for the work-up for peripheral arterial disease.

Diagnostiek en therapie in beeld: kennis, keuzes en kunst (Inaugural Lecture)

1999-09-23T00:00:00Z

Health-related quality of life after angioplasty and stent placement in patients with iliac artery occlusive disease: results of a randomized controlled clinical trial. The Dutch Iliac Stent Trial Study Group (Article)

1999-01-01T00:00:00Z

BACKGROUND: To assess the quality of life in patients with iliac artery occlusive disease, we compared primary stent placement versus primary angioplasty followed by selective stent placement in a multicenter randomized controlled trial. METHODS AND RESULTS: Quality-of-life assessments were completed by 254 patients in a telephone interview. Assessment measures consisted of the RAND 36-Item Health Survey 1.0, time tradeoff, standard gamble, rating scale, health utilities index, and EuroQol-5D. The interviews were performed before treatment and after 1, 3, 12, and 24 months. When the 2 treatments were compared, no significant difference was observed (P>0.05). All measurements showed a significant improvement in the quality of life after treatment (P<0.05). The RAND 36-Item Health Survey measures physical functioning, role limitations caused by physical problems, and bodily pain and the EuroQol-5D were the most sensitive to the impact of revascularization. CONCLUSIONS: Health-related quality of life improves equally after primary stent placement and primary angioplasty with selective stent placement in the treatment of intermittent claudication caused by iliac artery occlusive disease.