Self-reported activity limitations were measured with the physical function subscale of the Western Ontario and McMaster Universities Osteoarthritis Index. In all analyses we adjusted for age, gender, marital status, education level, radiographic OA and comorbidity. B (95% CI), Regression coefficient ( 95% confidence interval). β, Standardized regression coefficient. Semi-partial r2 = squared semi-partial correlation coefficient. BMI, Body-mass index. HADS, Hospital Anxiety and Depression Scale.