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 study of 480 adults over 65 years of age. Measurements of strength, sociodemographic characteristics, disease burden (including radiographic knee osteoarthritis [OA]), self-reported disability, and functional limitations were obtained 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 effect disappeared after accounting for baseline levels of knee pain intensity and knee strength.

CONCLUSION

Knee pain intensity and knee strength may mediate the relationship between radiographic evidence of knee OA and change in performance. Although it is not clear whether joint disease precedes or follows a decline in muscular strength, these results may help to identify subpopulations of older persons with knee OA who may benefit from interventions aimed at slowing the progression of disability related to transfer and ambulatory-based tasks.