Prevalence, Risk Factors, and Outcomes of Chronic Diseases in Adults with Intellectual Disabilities: A Scoping Review of Primary Care Evidence

Background: Adults with intellectual disabilities (ID) experience higher rates of chronic diseases compared to the general population. Yet, evidence on the prevalence, risk factors, and outcomes of these conditions in primary care settings remains fragmented. This scoping review aims to map the existing literature and identify key themes related to chronic diseases among adults with ID. Methods: A comprehensive search was conducted across five electronic databases— Embase, Medline, PubMed, Web of Science, and PsycINFO —from inception to May 2024. Studies were included if they focused on the prevalence, risk factors, or outcomes of chronic diseases in adults (aged 18 or older) with intellectual disabilities and were based on primary care evidence. A total of 1,365 records were initially identified. After duplicate removal, screening, and full-text assessment, eligible studies were charted and thematically analyzed following the Arksey and O'Malley framework. Results: The included studies reported a high prevalence of chronic conditions such as ischemic heart disease, cerebrovascular disease, diabetes, and chronic obstructive pulmonary disease (COPD) among adults with ID. Risk factors included age, sedentary lifestyle, poor diet, comorbid mental health conditions, and limited access to tailored healthcare services. Outcomes often included reduced quality of life, increased hospitalizations, and premature mortality. Variation in diagnostic criteria, healthcare access, and recording practices across primary care settings posed challenges in data comparability. Conclusions: Adults with intellectual disabilities face a disproportionate burden of chronic diseases, with multifactorial risk profiles and significant adverse outcomes. Primary care systems must adopt more inclusive practices, implement early screening strategies, and provide tailored interventions to reduce health disparities in this vulnerable population. Further research is needed to strengthen the evidence base and inform policy and practice.