Physical Activity in Persons With Arthritis

Research Design Overview This five-year study is a randomized controlled trial of 480 clients with arthritis conducted at three sites on the Northwestern University Feinberg School of Medicine campus, the Rehabilitation Institute of Chicago Arthritis Center (RIC-AC), the Northwestern Medical Faculty Foundation Rheumatology Division Ambulatory Center (NMFF-Rheum), and the NMFF General Internal Medicine Ambulatory Center (NMFF-GIM). After a 6 month startup period, two hundred forty clients with RA (120 from RIC-AC and 120 from NMFF-Rheum) and 240 clients with knee OA (120 from RIC-AC, 60 from NMFF-Rheum, and 60 from NMFF-GIM) will be recruited over a 24 month period, and each subject will be followed for 24 months. Randomization will be stratified by diagnosis, site, and disease-specific physical functional status. Half the clients will be randomized to the PAM intervention and half to the control intervention.

Independent variables include demographic characteristics, arthritis severity and comorbid conditions, and other IMCHB model variables: motivation (self-regulation efficacy), cognitive appraisal (perceived competency), and affective response (mental health). Outcomes measured by blinded interviewers/assessors include self-reported and objective measures of physical activity, self-reported measures of disease specific and generic health-related quality of life, and observed measures of physical function. All independent variables and outcomes are measured at baseline and nearly all independent variables and all outcomes are measured at 3, 6, 12, 18, and 24 months of follow-up. The primary analysis tests the effectiveness of PAM compared to control groups in improving disease-specific health related quality of life (HRQOL). Secondary analyses test 1) the effectiveness of PAM compared to control groups in improving generic HRQOL, 2) the effectiveness of PAM compared to control groups in improving observed measures of function and cardiovascular fitness, 3) the effectiveness of PAM compared to control groups in increasing physical activity performance, 4) whether PAM's effectiveness in improving HRQOL is mediated by it's ability to increase physical activity and 5) whether PAM's effectiveness in improving physical activity performance is mediated by changes in theory-based motivation variables.

Description and justification of the study population Given that there are more than 100 different forms of arthritis (defined here as any chronic condition affecting the joints and surrounding tissues), we have chosen clients with two well-defined and pathophysiologically distinct diseases to study, knee osteoarthritis (OA) and rheumatoid arthritis (RA). Knee OA is a prototype of a chronic degenerative arthropathy that has a high prevalence and is associated with a great amount of disability. RA is a prototype of the most common chronic inflammatory arthropathy, again associated with a high rate of disability. We expect that if the PAM program is effective in improving the physical activity and health status levels of these two distinctly different groups of arthritis clients, then it should be effective for many other, if not all, other arthritis clients.

Case definitions. Classification criteria developed by the American College of Rheumatology (ACR) will be used for clients with both knee OA and RA. The criteria utilizing knee x-rays will be used to increase the specificity of the knee OA criteria. These are standard case definitions that are used routinely in the rheumatology literature and have been shown to have high sensitivity and specificity.108, 109 Selection criteria. Clients fulfilling the ACR criteria for knee OA or RA will be eligible for this trial if the meet the following criteria: 1) age 18 or older, 2) able to ambulate at least household distances (50ft), and 3) able to speak and understand English, 4) no plans for total joint replacement in the following 12 months, 5) no contraindication to physical activity due to a comorbid conditions, and 6) no plans to relocate away from the Chicago land area for at least 24 months.

Methods for recruiting, enrolling, and sustaining participation. The Rehabilitation Institute of Chicago Arthritis Center (RIC-AC) and the Rheumatology and General Internal Medicine Divisions of the Northwestern Medical Faculty Foundation (NMFF-Rheum and NMFF-GIM), the practice of fulltime Northwestern University Feinberg School of Medicine faculty members, will be the sites where clients will be recruited for this trial. While on the same campus, these RIC and NMFF are physically separated from one another and have separate administrative structures.