Diagnosis, prevalence and associated factors of osteoarthritis in adults with intellectual disabilities

Background Osteoarthritis (OA) is a common and complex age–related chronic joint disease that leads to functional decline, loss in quality of life and a substantial health burden to affected individuals, health-care systems, and wider socioeconomic costs. Hip and knee OA are the most disabling types of OA, and knee OA is the most frequent site of symptomatic OA. Pain is the most dominant symptom of OA, but this condition is also characterized by joint tenderness, crepitus, stiffness, limitation of movement and variable degrees of local inflammation. Risk factors for OA are highly prevalent in people with intellectual disabilities (ID) (such as obesity, and poor physical fitness levels), and we therefore suspect a high prevalence of this condition in people with ID. However, little is known about the prevalence in people with ID, and difficulties in diagnosing OA in adults with ID hinders professionals in providing the best suitable care, and limits people with ID from receiving the care they need. For this reason there is a strong need for knowledge about how to properly diagnose OA in adults with ID, and about the prevalence of this condition, it’s associated factors. Aim To distil knowledge about how to properly diagnose OA of hip and knee in adults with ID, the prevalence of hip and knee OA in this population, and possible associated factors and or relationships with other relevant health outcomes and/or comorbidities. Method Cross-sectional study in adults with varying levels of ID, and living arrangements. The participants of this study all participated ten years ago in the baseline measurements of the ‘Healthy Ageing and Intellectual Disability’ (HA-ID/GOUD) study and still receive support from one of three participating ID care organizations affiliated with the HA-ID consortium. This study is part of the 10-year follow-up of the HA-ID study. The feasibility, test-retest reliability, and concurrent validity of measurements based on diagnostic criteria for OA of the American College of Rheumatology (ACR criteria) are studied in adults with ID. Based on these findings, the prevalence of radiographic and clinical OA in adults with ID is examined and the prevalence is compared with the prevalence of OA found in the general population. Finally, associations between OA and potential risk factors, relevant health outcomes and comorbidities are investigated in adults with ID. To thoroughly investigate the diagnostic criteria and potential associated variables, various measurements are used: physical examination, radiography, questionnaires, observations, physical measurements, blood samples, etc. Implementation The results of this study will be disseminated in various ways in cooperation with different partners, both through (international) publications and presentations and in the form of an easy-to-understand information brochure, and short contributions for websites and magazines. The results will also be incorporated in the curricula of the specialist education of ID physicians and general practitioners. Results will be implemented in the three participating ID care organizations through local project teams in close collaboration with the research team with a focus on sustainable implementation of scientific products that are relevant to clinical practice. In addition, the results and recommendations of this study will be implemented in the treatment consensus about the applicability of the national OA guideline for physical therapists in people with ID, developed by the Dutch Association of Physical Therapists for people with ID (NVFVG). Gaps of knowledge will be identified and will be the basis for future research.