The course of limitations in activities in patients with knee and hip osteoarthritis: risk factors for future functional decline.

Purpose: To describe the course of limitations in activities over five years follow-up and identify predictors of future limitations in activities in elderly patients with osteoarthritis (OA) of the hip or knee. Relevance: Although cross sectional research on determinants of limitations in activities is robust in patients with OA, high quality longitudinal research on the course of limitations in activities over time and predictors of future limitations in activities is surprisingly limited. Knowledge about the courseof limitations in activities over time and predictors of future limitations in activities is important for both patients and clinicians. Based on this information clinicians can identify patients who are at risk for future functional decline and prognosticate future limitations in activities. Furthermore, more insight in the course of limitations in activities and predictors of future limitations in activities is the basis for improving treatments and rehabilitation of patients with osteoarthritis of the hip or knee. Participants: Elderly patients with hip and/or knee osteoarthritis according to radiological criteria or clinical criteria of the American College of Rheumatology (n = 288) were recruited at rehabilitation centres and hospitals. Methods: A longitudinal cohort study with five years follow-up was conducted. The main outcome measures were self-reported and performance based limitations in activities. Prognostic factors were demographic and clinical data, body functions, co morbidity, cognitive functioning, avoidance of activity and social support. Measurements were conducted at baseline, 1, 2, 3 and 5 years follow-up. Analysis: All analyses were performed using generalized estimating equations (GEE). To identify predictors of future limitations in activities, univariate GEE analyses were performed. Potential predictors with a univariate p-value that was less than or equal to 0.15 were entered into a multivariable model, after which backward elimination of predictors was used to remove non-significant predictors (p to remove≥0.10). All analyses were performed separately for patients with knee OA and patients with hip OA. Results: Both in patients with knee and hip OA, the course of limitations in activities remained fairly stable over a period of five years. Avoidance of activity, increased pain, a higher morbidity count, a higher age, a longer disease duration, a reduced muscle strength and range of joint motion at baseline predicted more future limitations in activities in patients with knee OA. In patients with hip OA, avoidance of activity, increased pain, a higher morbidity count, a higher age, a higher educational level and a reduced muscle strength at baseline predicted more future limitations in activities. Conclusions: The course of limitations in activities remains fairly stable over a period of five years in elderly patients with hip or knee osteoarthritis. However, at individual level there is considerable variation. Predictors of more future limitations in activities include avoidance of activity, increased pain, higher morbidity count, lower muscle strength, and a higher age. Implications: The study findings can help clinicians prognosticate future limitations in activities in patients with hip or knee OA and identify patients who are at risk for more future limitations in activities. (aut. ref.)