Improving maintenance of physical activity in older, knee osteoarthritis patients trial-pilot (IMPACT-P): design and methods

Promoting increased physical activity participation is now consistently advocated in the medical management of knee osteoarthritis (OA). Unfortunately, physical activity interventions targeting older knee OA patients are plagued by high attrition rates and poor long-term adherence. Consequently, identifying effective approaches for promoting maintenance of physical activity participation is integral for the successful behavioral management of knee OA. The present study, the Improving Maintenance of Physical Activity in Knee Osteoarthritis Pilot Trial (IMPACT-P), was a single-blind two-arm, randomized controlled pilot study designed to contrast the effects of a group-mediated cognitive behavioral (GMCB) exercise intervention with those of traditional center-based exercise therapy approach (TRAD) in older, knee OA patients. A total of 80 older adults with symptomatic knee OA were randomly assigned to GMCB or TRAD interventions. The primary outcome of the IMPACT-P study was changed in self-reported (CHAMPS questionnaire) and objectively assessed (LIFECORDER EX Plus) physical activity participation of moderate intensity or greater. Secondary outcomes include physical function, quality of life, and social cognitive variables. Outcomes were obtained at baseline, 3 month, and 12 month assessments by trial personnel blinded to participants' randomization assignment. Discussion. Determining the comparable efficacy of the GMCB and TRAD exercise interventions in producing meaningful improvements in physical activity and OA outcomes could enhance the efficacy of implementing physical activity participation in the behavioral management of symptomatic knee OA.