Association between metabolic conditions, physical activity and self-efficacy before and after a first-line exercise and education intervention for osteoarthritis: a longitudinal register study using the SOAD cohort.

Objectives: To investigate the association of diabetes, hypertension and overweight/obesity with physical activity (PA), self-efficacy for pain and self-efficacy for other symptoms before and after a 6- week exercise and education intervention for knee and hip osteoarthritis (OA), and to assess outcome disparities based on metabolic health.

Methods: Register-based cohort study using the Swedish Osteoarthritis and Diabetes cohort. We used Body Mass Index, medical records and medication dispensation to define overweight/obesity, hypertension and diabetes at baseline (exposures). PA was self-reported (weekly minutes), and self-efficacy was measured using the 'Arthritis Self-Efficacy Scale' (ASES) (score 10-100) (outcomes). We used linear mixed-effect models to estimate associations between exposures and outcomes, adjusted for confounders.

Results: We included 80 893 individuals with knee or hip OA. Those with metabolic conditions consistently showed lower PA and self-efficacy, with baseline disparities persisting after the intervention, particularly when all three conditions coexisted (PA difference: baseline 107 min [95% CI: 97; 118], 3-month 97 [86; 108], 12-month 109 [95; 123]; ASES-pain difference: baseline 5.6 [3.9; 7.3], 3-month 5.9 [4.1; 7.7], 12-month 8.2 [6.1; 10.4]; ASES-other symptoms difference: baseline 6.1 [4.6; 7.7], 3-month 6.4 [4.8; 8.0], 12-month 8.2 [6.3; 10.1]).

Conclusions: Metabolic conditions were associated with lower PA and self-efficacy, with differences increasing with the number of co-existing conditions. The baseline disparities associated with metabolic conditions persisted after the intervention, with both groups showing improvement at 3 months but reverting to baseline by 12 months. This suggests that current guideline-based interventions for OA may not reduce long-term disparities related to metabolic conditions.