One third of Japanese patients with rheumatoid arthritis use complementary and alternative medicine.

We investigated the prevalence and predictors of complementary and alternative medicine (CAM) use by patients with rheumatoid arthritis (RA) in Japan. A cross-sectional descriptive study was performed using the database from a large observational cohort of RA patients in the Institute of Rheumatology, Tokyo Women's Medical University. Logistic regression analysis was carried out to reveal predictive factors for CAM use. Among 3815 RA patients, 1321 (34.6%; 174 males, 1147 females) used at least one type of CAM. Health foods, including dietary supplements, were the most commonly used. CAM was more frequently used by female patients (odds ratio: 0.578; 95% confidence interval [CI] = 0.451-0.740). A multiple logistic regression analysis revealed that sex (odds ratio: 0.489; 95% CI = 0.333-0.718) and degree of satisfaction with disease-modifying antirheumatic drugs (DMARDs) (odds ratio: 0.899; 95% CI = 0.852-0.948) were significant independent predictive factors for CAM use. The serum C-reactive protein level and erythrocyte sedimentation rate showed no significant associations with CAM use. Approximately 35% of RA patients used CAM in Japan. Female patients and patients dissatisfied with DMARDs used CAM more frequently, regardless of their disease activity.