To explore the associations between body composition and pain, disease activity, and disability in rheumatoid arthritis (RA).
The study enrolled 335 patients with RA and underwent body composition measurement with an InBody analyzer. The associations of body mass index (BMI), body fat mass, and skeletal muscle mass with disease activity score in 28 joints (DAS28), an index derived to measure the subjective component of DAS28 (DAS28-P), a pain visual analogue scale (VAS), and disability measured with the health assessment questionnaire (HAQ) were explored. Obesity was defined as BMI ≥ 25 kg/m2.
The median (interquartile range) disease duration was 6 years (3.5 to 9) and the mean DAS28 score was 3.6 ± 1.1. The mean BMI was 23.6 ± 3.6 kg/m2 and 109 patients (32.5%) were obese. Compared with non-obese patients, obese patients had a higher C-reactive protein (1.68 mg/dL vs. < 0.1 mg/dL, p = 0.013), higher pain VAS score (40 vs. 35, p = 0.031), and higher DAS28-erythrocyte sedimentation rate score (3.75 ± 1.18 vs. 3.46 ± 1.11, p = 0.031). In multivariate regression analysis, the DAS28 score in females was positively associated with the current steroid dose, body fat mass, and HAQ score, while the HAQ score in females was associated with older age, DAS28, lower skeletal muscle mass, and higher body fat/skeletal muscle ratio. In the multivariate regression analysis, the DAS28-P score in females was positively associated with body fat/skeletal muscle ratio and HAQ.
Body composition, such as the body fat mass and body fat/skeletal muscle ratio, is significantly associated with disease activity and disability in female RA patients.