Sarcopenia in rheumatoid arthritis: prevalence, influence of disease activity and associated factors

Evaluate the prevalence of sarcopenia on patients with rheumatoid arthritis (RA), the influence of sarcopenia on disease activity and factors associated with sarcopenia. One hundred and twenty-three patients aged over 18 years with RA based on the 1987 ACR/EULAR classification criteria were enrolled. We performed a whole body DXA scan using a dual-energy X-ray absorptiometry (DXA) scanner lunar prodigy to measure fat mass, lean mass, and bone mass in the whole body and body parts. According to the anthropometric equation by Baumgartner et al., sarcopenia was defined as Relative skeletal mass index (RSMI) <5.5 kg/m² on women and <7.26 kg/m² on men. Body mass index (BMI) and waist circumference were measured and patients were classified according to World Health Organization. Disease activity was evaluated by: disease activity score 28 ESR (DAS28 ESR), disease activity score 28 CRP (DAS28 CRP), clinical disease activity index (CDAI), simplify disease activity index (SDAI). We measured functional disability by Health assessment questionnaire (HAQ). History and previous medication use including steroids were also checked, and comorbidities were recorded. We analyzed the relation between disease parameters and sarcopenia with the r of Pearson and Spearman. Factors associated and related to sarcopenia were assessed using multiple regression analysis and t independent test. We included 123 patients (107 women). 49 subjects (39.8%) where suffering from sarcopenia, of which 40 women. Most of the sarcopenic patients were between 41 and 50 years old. Sarcopenia on female subjects was not related to parameters of disease activity evaluated by DAS 28, CDAI and SDAI. Most of the sarcopenic patients had normal BMI and abnormal waist circumference. In simple regression analysis sarcopenia was related to BMI, DAS 28 ESR, bone erosion, waist circumference and HAQ. In multiple regression analysis, sarcopenia was positively related to an increase cardiometabolic risk [p = 0.025, OR 0.176, CI (0.038-0.980)], normal BMI [p = 0.004, OR 12.3, CI (2.27-67.6)], over fat BMI [p = 0.004, OR 12.3, CI (2.27-67.6)] and bone erosion [p = 0.012, OR 0.057 CI (0.006-0.532)]. No statistical difference was found according to disease duration and steroids use between sarcopenic and non sarcopenic patients. Sarcopenia is prevalent and related to age, bone erosion, normal/over fat BMI and high cardiometabolic risk according to waist circumference but not with disease activity.