Improving physical activity in arthritis clinical trial (IMPAACT): Study design, rationale, recruitment, and baseline data

Over 21 million Americans report an arthritis-attributable activity limitation. Knee osteoarthritis (OA) and rheumatoid arthritis (RA) are two of the most common/disabling forms of arthritis. Various forms of physical activity (PA) can improve a variety of health outcomes and reduce health care costs, but the proportion of the US population engaging in the recommended amount of PA is low and even lower among those with arthritis.The Improving Motivation for Physical Activity in Arthritis Clinical Trial (IMPAACT) is a randomized clinical trial that studied the effects of a lifestyle PA promotion intervention on pain and physical function outcomes. The IMPAACT intervention was based on a chronic care/disease management model in which allied health professionals promote patient self-management activities outside of traditional physician office encounters. The program was a motivational interviewing-based, individualized counseling and referral intervention, directed by a comprehensive assessment of individual patient barriers and strengths related to PA performance. The specific aims of IMPAACT were to test the efficacy of the IMPAACT intervention for persons with arthritis (N = 185 persons with RA and 155 persons with knee OA) in improving arthritis-specific and generic self-reported pain and Physical Function outcomes, observed measures of function, and objectively measured and self-reported PA levels. Details of the stratified-randomized study design, subject recruitment, and data collection are described. The results from IMPAACT will generate empiric evidence pertaining to increasing PA levels in persons with arthritis and result in widely applicable strategies for health behavior change.