The impact of physical activity level on the short- and long-term pain relief from supervised exercise therapy and education: a study of 12,796 Danish patients with knee osteoarthritis

Objectives: It is unknown if people with knee osteoarthritis (OA) who are already physically active benefit from exercise therapy. To study the impact of physical activity level on pain relief, post-intervention and 12 months following exercise therapy and education. Method: The analyses included 12,796 patients with knee OA from the Good Life with osteoArthritis in Denmark (GLA:D^®) program. GLA:D^® consists of 12 sessions of supervised neuromuscular exercise and two sessions of education delivered by trained physical therapists. The impact of physical activity level on change in knee pain intensity (0–100) immediately post-intervention and at 12 months was estimated using a mixed-effects model adjusted for age, sex, body mass index (BMI), educational level and comorbidity. Physical activity level was assessed using the University of California, Los Angeles (UCLA) activity scale. Results: Physically inactive patients had worse baseline pain compared to patients with low to very high physical activity level (6–15 points worse; P < 0.001). Pain decreased by 13.4 points (95% CI; 9.7 to 17.1) following the treatment program and by 12.8 points (7.7–18.0) at 12 months in the inactive patients, with similar improvements in patients with higher levels of physical activity (P = 0.278 to 0.851). Conclusion: In patients with knee OA, similar and persistent long-term pain relief was found from supervised exercise therapy and education regardless of the initial physical activity level. Patients with high to very high levels of physical activity can expect pain relief from supervised exercise therapy and education similar to that of more physically inactive patients.