Elsevier

Thrombosis Research

Volume 123, Issue 5, March 2009, Pages 771-774
Thrombosis Research

Regular Article
Comparison of the clinical usefulness of two quantitative D-Dimer tests in patients with a low clinical probability of Pulmonary Embolism

https://doi.org/10.1016/j.thromres.2008.07.014Get rights and content

Abstract

Background

Quantitative D-Dimer tests are established methods in the non-invasive diagnostic management to rule out venous thromboembolism (VTE). The diagnostic performance and the clinical efficiency different D-Dimer assays in the exclusion of pulmonary embolism (PE) have not yet been compared in a clinical outcome study.

Objective

Evaluation of the efficiency and safety of excluding the diagnosis of PE with two different quantitative D-Dimer assays in consecutive patients with clinically suspected PE.

Patients and Methods

We studied the VTE-failure rate of 2206 consecutive patients with an unlikely clinical probability in whom VIDAS or Tinaquant D-Dimer tests were performed.

Results

The prevalence of PE in 1238 patients whose D-Dimer level was analyzed with Tinaquant assay was 11%. The VIDAS assay group consisted of 968 patients with a PE prevalence of 13%. The VIDAS assay had a sensitivity of 99.2% (95%CI; 96- > 99.9%), the Tinaquant assay of 97.3% (95%CI; 93 -99%). The negative predictive value (NPV) in the Tinaquant assay group was 99.4% (95%CI 98-99.8%) in comparison to 99.7% (95%CI 99-> 99.9%) in the VIDAS assay group. During 3 month of follow-up, there were no fatal cases of PE among patients with normal D-Dimer and unlikely clinical probability in both D-Dimer assay groups. In addition, the test efficiency of Tinaquant assay was significantly higher in comparison to VIDAS assay (52% vs 42%, p < 0.001).

Conclusion

Both Tinaquant and VIDAS D-Dimer tests perform equally well in combination with an unlikely clinical probability in excluding PE. The Tinaquant test was shown to be more efficient.

Introduction

D-Dimer assays have an established role in the diagnostic approach of venous thrombo-embolism. D-Dimer test in combination with the determination of clinical pretest probability is increasingly accepted as a first-line test in patients with suspected pulmonary embolism (PE) [1], [2], [3], [4], [5], [6]. Several management studies have shown that PE can be safely ruled out without the need for additional imaging in patients with an unlikely clinical pretest probability according to Wells (Table 1) and a normal D-Dimer test result, occurring in 20% to 40% of patients [6], [7], [8].

When choosing a specific D-Dimer test, it is important to consider both sensitivity and specificity of the assay. Most quantitative D-Dimer tests are very sensitive but specificity is generally relatively poor [9], so that a normal result has high negative predictive value but occurs in a relatively small proportion of patients. Differences between D-Dimer assays are caused by antibody specificity, especially concerning the preference for high- or low-molecular-weight fibrin derivates and for cross-linked and non-cross-linked fibrin derivates [10]. Other causes of discrepancies between D-Dimer assays are thought to be the time-dependency of neo-epitope expression in the course of fibrin formation and dissolution, assay format, purity or heterogeneity of the calibrator, matrix effects of plasma on epitope presentation and interference by irrelevant analysis [11].

Importantly, although there is a wealth of studies evaluating different D-Dimer tests in the setting of venous thrombosis and pulmonary embolism, a comparison between two tests in a clinical outcome study has not been carried out.

We conducted a post-hoc analysis from data that were derived from a prospective cohort study, the Christopher study [6]. Within this study we evaluated the clinical usefulness and test efficiency of the two quantitative D-Dimer tests used in this study, the latex (Tinaquant) D-Dimer test and the quantitative ELISA (VIDAS) plasma D-Dimer test.

Section snippets

Patients

Consecutive in- and outpatients with clinically suspected pulmonary embolism were eligible for the Christopher study. Patients were excluded if they had received treatment with therapeutic doses of unfractionated or low-molecular-weight-heparin for more than 24 hours, had a life expectancy less than 3 months, were pregnant, had geographic inaccessibility precluding follow-up an age below 18 years, an allergy to intravenous contrast agents, a renal insufficiency (creatinine clearance 30 mL/ min

Results

In the total study population, consisting of 2206 patients, a D-Dimer concentration was measured in 1238 patients using the Tinaquant D-Dimer assay and in 968 patients using the VIDAS D-Dimer assay. The general characteristics of both groups were comparable (Table 2). Of the 1057 patients with a normal D-dimer test result, 29 (11 in the Tinaquant group and 18 in the VIDAS group) were treated with oral anticoagulants during follow-up for other reasons than venous thrombosis. Also, 2 patients

Discussion

This analysis shows that in patients with an unlikely clinical probability of PE according to the Wells Rule, the quantitative Tinaquant and VIDAS D-Dimer tests performed equally well in excluding PE. Both tests had very low VTE failure rates at follow up, 0.62% for the Tinaquant and 0.24% for the VIDAS. Also, in neither group fatal PE occurred during follow-up. Our results are in contrast with earlier studies, in which the VIDAS test was shown to have a better sensitivity and NPV than

Conflict of interest

The authors declare to have no financial disclosure to this manuscript which they should report.

Acknowledgements

The Christopher Study Writing Group consisted of the following investigators in alphabetical order: Arne van Belle, Harry R. Büller, Menno V. Huisman, Peter M. Huisman, Karin Kaasjager, Pieter W. Kamphuisen, Mark H.H. Kramer, Marieke J.H.A. Kruip, Johanna M. Kwakkel-van Erp, Frank W.G. Leebeek, Mathilde Nijkeuter, Martin H. Prins, Maaike Sohne, Lidwine W. Tick.

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