Characteristics of Appendicular Tissue Components in Patients with Rheumatoid Arthritis

BACKGROUND: The purpose of this study was to identify the characteristics of appendicular lean mass (ALM) associated with rheumatoid arthritis (RA) and to analyze appendicular tissue components in patients with RA. METHODS: We prospectively reviewed of patients with RA who underwent dual energy X-ray absorptiometry in a single center. From data of 28 patients, ALM was calculated. Regression analysis was used to investigate the association between ALM and RA. Using propensity score matching, patients with RA were compared to the control group from 18,698 patients of Korea National Health and Nutrition Examination Surveys data. RA and control group were matched in a 1: 5, respectively. RESULTS: In regression model, there was significantly negative association between disease activity score and ALM index in patients with RA in unadjusted (β=−0.387, 95% confidence interval [CI], −0.729 to −0.045) and model adjusted for age, sex, and body mass index (β=−0.227, 95% CI, −0.451 to −0.003). In matching with age and sex, the arms fat mass and fat fraction of RA group were significantly lower than that of control group. In matching with age, sex, and body mass index, the ALM index and legs lean mass of RA group were significantly higher than control group. CONCLUSIONS: Patients with RA have a lower ALM with higher disease activity. In addition, we found that patients with RA had different tissue component in arms and legs compared to general population.