With increasing longevity and cardiovascular events, chronic kidney disease may also become a significant problem in older people with intellectual disability (ID). We studied prevalence and associations of chronic kidney disease as part of the Healthy Ageing and Intellectual Disability (HA-ID) study, a large Dutch cross-sectional study among people with ID aged 50 years and over, using creatinine and cystatin-C measurement in plasma. Glomerular filtration rate (GFR) 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 GFR 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. GFR 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.
Keywords: Down syndrome; Intellectual disability; Kidney disease; Prevalence; Renal dysfunction.
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