Evaluation of Dynamic Effects of Depressive Symptoms on Physical Function in Knee Osteoarthritis.

ABSTRACT

OBJECTIVE: To assess how changes in depressive symptoms influence physical function over time among those with radiographic knee osteoarthritis (OA). METHODS: Participants from the Osteoarthritis Initiative with radiographic knee OA (n = 2,212) and complete data were identified at baseline. Depressive symptoms were assessed as a time-varying score at baseline and the first three annual follow-up visits using the Center for Epidemiological Studies Depression Scale (CES-D) Scale. Physical function was measured at the first four follow-up visits using 20-meter gait speed meters per second. The following two marginal structural models were fit one assessing the main effect of depressive symptoms on gait speed and another assessing time-specific associations. RESULTS: Time-adjusted results indicated that higher CES-D scores were significantly associated with slower gait speed (-0.0048; 95% confidence interval -0.0082 to -0.0014), and time-specific associations of CES-D were largest during the first follow-up interval (-0.0082; 95% confidence interval -0.0128 to -0.0035). During subsequent follow-up time points, the influence of depressive symptoms on gait speed diminished. CONCLUSION: The negative effect of depressive symptoms on physical function may decrease over time as knee OA progresses.