The Impact of Self‐Efficacy on Activity Limitations in Patients With Hip Osteoarthritis: Results From a Cross‐Sectional Study

OBJECTIVE: Pain and activity limitations are the main health complaints in osteoarthritis. We explored pathways between pain and activity limitations in a chain mediation model that involved self‐efficacy, physical activity behavior, and muscle function in patients with hip osteoarthritis not awaiting hip replacement. METHODS: We used cross‐sectional, baseline data from a randomized controlled trial on 152 patients with clinical hip osteoarthritis according to the American College of Rheumatology not awaiting hip replacement. The associations between pain, self‐efficacy, self‐reported physical activity, muscle function (leg extensor power), and activity limitations (performance‐based and self‐reported activity limitation outcomes) were modeled using structural equation models. RESULTS: The effect of pain on performance‐based activity limitation was fully mediated by self‐efficacy, physical activity, and muscle function. Of the total effect of self‐efficacy on performance‐based activity limitation, the direct effect accounted for 63% (95% CI: 45%‐82%), whereas the indirect effect via physical activity constituted 16% (95% CI: 1%‐30%) and the indirect effect via muscle function constituted 21% (95% CI: 9%‐32%). In contrast, physical activity and muscle function had no effect on self‐reported activity limitations, whereas pain had a direct effect and an indirect effect mediated by self‐efficacy. CONCLUSION: Our results suggest that self‐efficacy should be taken into consideration in prevention and treatment of activity limitations in patients with hip osteoarthritis not awaiting hip replacement. Coupling exercise with programs of self‐efficacy enhancement could potentially increase the positive effects of exercise.