Rafaela Cavalheiro do Espírito Santo, Daniel Nóbrega de Moraes, Lucas Denardi Dória, Leonardo Peterson dos Santos, Émerson Pena, Stephanie Pilotti, André Mallmann, Vanessa Hax, Nicole Pamplona Bueno de Andrade, Poli Mara Spritzer, Tayane Muniz Fighera, Joshua F. Baker, Rafael Mendonça da Silva Chakr, Claiton Viegas Brenol, Ricardo Machado Xavier
BACKGROUND: Rheumatoid arthritis (RA) is a systemic autoimmune disease with articular and extra-articular manifestations. Chronic inflammation may contribute to sarcopenia independently of age. While cross-sectional studies report sarcopenia in 24-30% of RA patients, longitudinal data remain limited. This study aimed to assess long-term changes in sarcopenia and body composition in RA patients and explore their associations with clinical features and health outcomes. METHODS: In this prospective cohort study, 90 RA patients were followed for a median of 6.4 years (IQR: 5.8-7.0). Clinical features, falls, fragility fractures, and mortality were recorded. Body composition (BMI, appendicular lean mass index [ALMI], fat mass index [FMI]) was assessed using dual-energy X-ray absorptiometry; grip strength by JAMAR dynamometer; and physical performance by the Timed Up and Go test. Sarcopenia was defined using EWGSOP2 criteria. Statistical analyses included ANOVA, Kruskal-Wallis, chi-squared tests, generalized estimating equations, Kaplan-Meier curves, and regression models. RESULTS: At baseline, mean age was 56.5 ± 7.3 years, median disease duration 8.5 years (IQR:3.0-18.0), median DAS28-CRP 3.0 (IQR:1.0-3.0), and mean HAQ-DI 1.1 ± 0.9. Seven patients (7.7%) had sarcopenia, including one severe case. Most participants were overweight with elevated FMI. Sarcopenia prevalence and clinical characteristics remained stable, with no new sarcopenia cases during follow-up. ALMI increases were associated with FMI increases (p = 0.005). Baseline sarcopenia was not associated with falls, fractures, or mortality. Low muscle mass and poor physical performance were not linked to mortality, but low muscle strength showed a trend toward higher mortality risk (HR = 4.35, 95% CI: 0.51-37.25). After adjusting for age, disease duration, glucocorticoid dose, and DMARD use, low muscle strength was significantly associated with falls (B = 3.92,95% CI:1.03-15.02;p = 0.046). No associations were found for low muscle mass, low physical performance, or sarcopenia with these outcomes. CONCLUSION: In RA patients receiving regular care, sarcopenia prevalence remained high and stable. Low muscle strength was associated with falls and showed a trend toward increased mortality risk, possibly due to limited sample size, highlighting its potential prognostic value. However, the absence of a control group limits interpretation, as observed changes may reflect normal aging rather than disease-specific effects. CLINICAL TRIAL NUMBER: Not applicable.