Cardiovascular Disease Risk Factors in Older People with Intellectual Disabilities

Abstract

Chapter 1 General introduction There is an increasing group of older people with intellectual disability in The Netherlands, reaching almost the same life expectancy as the general population. Age-related diseases, such as cardiovascular disease, cancer and dementia are now the most encountered diseases and causes of death in older people with intellectual disabilities. Although cardiovascular disease is a major risk for older people with intellectual disabilities, no reliable information was available on cardiovascular disease risk factors, nor attention for prevention of cardiovascular disease was present prior to the start of the Healthy Ageing and Intellectual Disability (HA-ID) study. The HA-ID study aimed at gaining knowledge on healthy ageing by studying health and health risks in an older population of people with intellectual disabilities. Three large care organizations and two university departments participated in this study. Subthemes in the HA-ID study were: (1) Physical activity and fitness, (2) Nutrition and nutritional state, and (3) Mood and anxiety. By studying these themes and the interrelationships, a comprehensive concept of health and health-needs in aging people with intellectual disability would be created. Through physical examination, laboratory examination, and use of screening and diagnostic psychiatric interviews, data were collected on 1050 participants, aged 50 years and over with borderline to profound intellectual disability, which was a near- representative sample for the total older population using formal intellectual disability care. This study was performed to give more insight into the prevalence and associations of cardiovascular risk factors, and the subsequent development of atherosclerosis, in older people with intellectual disability in a large unbiased population sample.

Chapter 2 Overweight and obesity As obesity is a major health problem associated with increased cardiovascular disease risks, the prevalence of overweight, obesity and body fat percentage in older people with intellectual disability through measurement of Body Mass Index (BMI), waist circumference, waist to hip ratio and skin fold thickness was studied and compared with prevalence of overweight and obesity in the general population. Associations of overweight and obesity with participant and treatment characteristics (gender, age, level of intellectual disability, Down syndrome, autism, independent living, smoking, (instrumental) activities of daily living, physical activity and use of atypical antipsychotic medication) were studied using regression analyses. Among 945 participants, overweight and obesity were highly prevalent, with more obesity (26%) than in the general Dutch older population (10%) as measured by BMI, and 46-48% obesity as measured by waist circumference and waist to hip ratio respectively. Women, people with Down syndrome, higher age, less severe ID, autism, people who are able to eat independently, preparing meals and doing groceries independently, people with physical inactivity and use of atypical antipsychotics were significantly more at risk of being overweight or obese.

Chapter 3 Hypertension, hypercholesterolemia, diabetes and the metabolic syndrome Hypertension, hypercholesterolemia and diabetes are important cardiovascular disease risk factors. Together with abdominal obesity they form the metabolic syndrome, which indicates metabolic disturbances, consisting of insulin resistance and accounting for a severe risk of cardiovascular disease. We determined the prevalence of cardiovascular risk factors and compared this with the prevalence in the same-aged general population. Furthermore we determined how many risk factors had not been previously diagnosed, and identified correlates of CVD risk factors (gender, age, level of ID, Down syndrome, independent living, activities of daily living, mobility, instrumental activities of daily living, physical activity, use of atypical antipsychotics, central obesity), using logistic regression analyses. Ninehundred-eighty people participated in this study. Hypertension (53%), diabetes (14%) and metabolic syndrome (45%) were present similarly as in the general Dutch population. Hypercholesterolemia was present less often (23%). Fifty percent of the people with hypertension had not been not previously diagnosed with this condition. Percentages for diabetes, hypercholesterolemia, and the metabolic syndrome were 45, 46 and 94 respectively. People who were more at risk for CVD risk factors were women, older people, people with obesity, people who lived more independently and people who were able to do groceries or prepare a meal independently.

Chapter 4 Peripheral arterial disease Peripheral arterial disease, atherosclerosis distal from the aortic bifurcation, is associated with increased cardiovascular morbidity and mortality. We determined the prevalence of peripheral arterial disease, the rate of prior diagnoses, and correlations with participant characteristics, and compared the prevalence with peripheral arterial disease in the general Dutch population. Peripheral arterial disease was defined as an ankle-brachial index <0.9. After excluding those, who met the exclusion criteria, 629 participants remained. Peripheral arterial disease was present in 20.7% of the participants and 97% had not been diagnosed before. People with higher age, smokers and people who lived in central settings, walked with support and who were more dependent in activities of daily living were more at risk of peripheral arterial disease. The prevalence is higher than in the general population (17.4% of 562 eligible participants with ID, as compared to 8.1% of 917 Dutch participants of the PANDORA study, a pan-European study into the prevalence of peripheral arterial disease) through all age groups.

Chapter 5 Association with anxiety and depression symptoms Depression and anxiety may be bidirectionally related to cardiovascular disease risk factors. Depression and anxiety may have biological effects causing glucose intolerance, fat accumulation and also lifestyle changes causing metabolic syndrome. But also the effects of diabetes, metabolic syndrome and subsequent cardiovascular disease may affect mood and anxiety. We studied the association between symptoms of anxiety and depression, among 990 participants who completed the screening instruments, with components of the metabolic syndrome, peripheral arterial disease and c-reactive protein. Of the 990 people who participated, 17% had symptoms of depression and 16% had symptoms of anxiety. In a multivariate logistic regression analysis a significant association was found between increased anxiety symptoms and diabetes only (OR 2.4, 95%CI 1.2-4.9).

Chapter 6 Chronic kidney disease Prevalence and associations of chronic kidney disease were studied using creatinine and cystatin-C measurement in plasma. Glomerular filtration rate was calculated using the Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. Equations based on creatinine (as the MDRD equation) may underestimate kidney dysfunction in people with sarcopenia, because low muscle mass leads to a low creatinine production. Therefore, also prevalence of chronic kidney disease was studied in the sarcopenic group, using different glomerular filtration rate equations. Prevalence of chronic kidney disease, among 635 participants, was 15.3%, which equals prevalence in the general Dutch population. In the group of participants with sarcopenia (n=82), the CKD-EPI equation based on creatinine and cystatin-C gave a higher prevalence of chronic kidney disease than did the MDRD equation, but confidence intervals were very wide. Chronic kidney disease was associated with higher age, Down syndrome, obesity, hypercholesterolemia and hypothyroid disease. Glomerular filtration rate should be measured in all older people with ID and polypharmacy, and in older people with ID and Down syndrome as part of the regular health checks. Moreover, if sarcopenia is present and information on GFR is required, this should not be measured based on creatinine only, but additional measures, such as cystatin-C, should be taken into account.

Chapter 7 General discussion Some important cardiovascular disease risk factors, which are also a burden of disease by themselves: peripheral arterial disease, diabetes and obesity (in women), occur more often among aging people with intellectual disability than in the same aged general population. Other risk factors, hypertension, metabolic syndrome, obesity in men and chronic kidney disease, occur as frequently as in the general population. People who live more independently are more at risk for cardiovascular disease risk factors, which reflects lifestyle related factors, such as physical inactivity and unhealthy diet choices. Other possible related factors in the intellectually disabled population (such as use of atypical antipsychotics, mood and anxiety disorders, circadian rhythm disturbances, low vitamin D, effects of inactivity of the large muscles, chronic inflammation and frailty) are discussed. This study has shown that everyone who works with or for older people with intellectual disabilities should be well aware of the cardiovascular disease risk. An anticipating preventive policy should be embedded in the whole care for people with intellectual disability. This includes education on healthy lifestyle for personal care givers and for people with mild levels of intellectual disability. Furthermore, care providing organizations should incorporate targeted health promotion programs in daily care and activities. General practitioners and specialized physicians for people with intellectual disabilities should perform pro-active cardiovascular risk management, starting before the client is aged 50 years. This includes screening for and treatment of cardiovascular risk factors, peripheral arterial disease and kidney dysfunction. Recommendations for future research are provided to improve knowledge and care on cardiovascular disease risk factors and subsequent cardiovascular disease for older people with intellectual disabilities.