Modifiers of change in physical functioning in older adults with knee pain: The observational arthritis study in seniors (OASIS)

Objective. To ascertain predictors of decline in physical functioning among older adults reporting knee pain. Methods. The Observational Arthritis Study in Seniors was a longitudinal st udy of 480 adults over 65 years of age. Measurements of strength, sociodemo graphic characteristics, disease burden (including radiographic knee osteoa rthritis [OA]), self-reported disability, and functional limitations were o btained on participants at baseline and at 15 and 30 months. Results. Radiographic evidence of OA at baseline was moderately associated with an increased decline in both transfer (P = 0.06) and ambulatory-based performance tasks (P = 0.04) but not in self-reported disability. This effe ct disappeared after accounting for baseline levels of knee pain intensity and knee strength. Conclusion. Knee pain intensity and knee strength may mediate the relations hip between radiographic evidence of knee OA and change in performance. Alt hough it is not clear whether joint disease precedes or follows a decline i n muscular strength, these results may help to identify subpopulations of o lder persons with knee OA who may benefit from interventions aimed at slowi ng the progression of disability related to transfer and ambulatory-based t asks.