To clarify the relationship among serum adiponectin, body composition, current disease activity and therapeutics of rheumatoid arthritis (RA).
We conducted a cross-sectional study in RA patients under treatment with agents including biological disease-modifying antirheumatic drugs (bDMARDs) and Janus kinase (JAK) inhibitors. A total of 351 subjects from the Kyoto University RA Management Alliance cohort (KURAMA) were enrolled in the analysis. We classified the participants into five body composition groups according to the cut-off points for obesity and visceral fat used in Japan: body mass index (BMI), 18.5 kg/m2 for underweight and 25.0 kg/m2 for obesity, and visceral fat area (VFA), 100 cm2 for visceral adiposity.
Classification of body composition revealed that serum adiponectin levels and disease activity score (DAS28-ESR) in the low BMI group were significantly higher than those in the normal and overweight groups. Because both increased serum adiponectin and low BMI were previously reported as poor prognostic factors of RA, we performed multiple regression analysis to determine which factor was correlated with RA disease activity. Serum adiponectin level, but not BMI, was positively associated with DAS28-ESR (estimate = 0.0127, p = 0.0258). Subanalysis also showed that the use of bDMARD or JAK inhibitor did not have an obvious influence on circulating adiponectin.
Classification of body composition and multiple regression analysis revealed a positive and independent correlation between serum adiponectin and DAS28-ESR in Japanese RA patients. Thus, serum adiponectin may be an important marker reflecting high disease activity of RA regardless of current medications.