Cognitive Mediators of Change in Physical Functioning in Response to a Multifaceted Intervention for Managing Osteoarthritis

PURPOSE: Although non-pharmacological interventions have been shown to improve physical functioning in individuals with osteoarthritis (OA), the mechanisms by which this occurs are often unclear. This study assessed whether changes in arthritis self-efficacy, perceived pain control, and pain catastrophizing mediated changes in physical functioning following an osteoarthritis intervention involving weight management, physical activity, and cognitive-behavioral pain management. METHOD: Three hundred Veteran patients of 30 primary care providers with knee and/or hip OA were cluster randomized to an OA intervention group or usual care. The OA intervention included a 12-month phone-based patient behavioral protocol (weight management, physical activity, and cognitive-behavioral pain management) plus patient-specific OA treatment recommendations delivered to primary care providers. RESULTS: Using linear mixed models adjusted for provider clustering, we observed that baseline to 6-month changes in arthritis self-efficacy and pain control partially mediated baseline to 12-month physical functioning improvements for the intervention group; catastrophizing did not. CONCLUSION: Findings of a mediating role of arthritis self-efficacy and pain control in intervention-related functional changes are consistent with hypotheses and align with theoretical assertions of the role of cognitions in cognitive and behavioral interventions for chronic pain. However, contrary to hypotheses, catastrophizing was not found to be a mediator of these changes.