To determine to what extent physical activity confounds the relation between race and the incidence of osteoarthritis (OA)-related functional limitation.
Osteoarthritis Initiative study participants, with or at increased risk of knee OA, who wore an accelerometer were included. Race was self-reported. Average time spent in moderate-to-vigorous physical activity (minutes/day) based on ActiGraph uniaxial accelerometer data was assessed. Functional limitation was based on: 1) inability to achieve a community walking speed (1.2 m/s) standard; 2) slow walking speed (<1.0 m/s); and 3) low physical functioning based on Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function score ≥28/68.
African Americans (AAs, n=226), compared to Whites (n=1348), had a higher likelihood of developing functional limitation based on various measures. When adjusted for time in moderate-to-vigorous physical activity, the association between AA race and inability to walk a community walking speed slightly decreased (from RR 2.15 [95% CI: 1.64-2.81] to 1.99 [95% CI: 1.51-2.61]). Association between AA race and other measures of functional limitation mildly decreased (slow walking speed: from RR 2.06 [95% CI: 1.40-3.01] to 1.82 [95% CI: 1.25-2.63]; low physical functioning: from RR 3.44 [95% CI: 1.96-6.03] to 3.10 [95% CI: 1.79-5.39]). When further adjusted for demographic and other clinical variables, only the association between race and low physical functioning (WOMAC) significantly decreased and no longer met statistical significance.
Greater physical activity is unlikely to completely make up for race differences in OA-related functional limitation, and other barriers to health equity need to be addressed. This article is protected by copyright. All rights reserved.

This article is protected by copyright. All rights reserved.