Prevalence and Associated Factors of Sarcopenia in Thai Rheumatoid Arthritis Patients

Background/Objectives Sarcopenia associates with poor health-related quality of life (HRQoL). This study aimed to determine prevalence and factors associated with sarcopenia in rheumatoid arthritis (RA) patients. The HRQoL between RA patients with and without sarcopenia also was compared. Methods This cross-sectional study recruited RA patients, aged ≥20 years, at Chiang Mai University Hospital between May and November 2023. Their skeletal muscle mass (bioelectrical impedance analysis), grip strength (hand dynamometer), and physical performance (gait speed test) were evaluated. Sarcopenia was defined according to the Asian Working Group for Sarcopenia. Patient characteristics, disease activity, physical disability (HAQ-DI), HRQoL (SF-36), nutrition (mini nutrition assessment), and medications were recorded. Results Of 299 patients (89.0% female; age 61.3 ± 11.6 years; disease duration 13.9 ± 8.6 years), 37.5% had sarcopenia (27.4% severe sarcopenia). In multivariable analysis, body mass index (odds ratio [95% confidence interval] 1.46/1 unit decrease [1.27, 1.68], p < 0.001), disease duration (1.89/10 years increase [1.27, 2.83], p = 0.002), deformity of hands/feet (3.80 [1.50, 9.61], p = 0.005), mini nutritional assessment score (1.21/1 score decrease [1.04, 1.40], p = 0.012), and high C-reactive protein (CRP) (1.94 [1.02, 3.69], p = 0.044) were independent factors associated with sarcopenia. There was no relationship between sarcopenia and disease activity (DAS-28-ESR or CRP) or medication use. RA patients with sarcopenia had higher HAQ score than those without, but potentially lower scores in physical function domain of SF-36 with adjusted mean difference of 0.2 (95% confidence interval 0.03, 0.32, p = 0.022) and −5.9 (−12.24, 0.38, p = 0.066), respectively. Conclusions About one third of the Thai RA patients in this center had sarcopenia. Low body mass index, long disease duration, joint deformity, malnutrition, and high CRP were independent factors associated with sarcopenia. Sarcopenia affects physical capabilities and the physical function domain of the HRQoL.