Background: Rheumatoid arthritis (RA) patients with low muscle mass (myopenia) have a higher risk of physical dysfunction and poor prognosis. However, the evidence of longitudinal changes in muscle mass in female RA patients was scarce. Objectives: This study aimed to explore the long-term muscle dynamics and their potential effectors in female RA patients. Design: A 5-year prospective cohort study. Methods: Female RA patients without a diagnosis of myopenia at baseline were included if they finished the time frame of 5-year follow-up and had at least 2 times of muscle assessments by bioelectric impedance analysis. Linear mixed-effect models (LMEM) were used to analyze the annual progression rates of the appendicular skeletal muscle index (ASMI). Results: There were 210 female RA patients included, with a mean age of 48.4 ± 10.9 years and a median disease duration of 48 (interquartile range (IQR) 19, 95) months. During the median follow-up time of 4.73 (IQR: 2.86–5.15) years, the multivariable-adjusted annual decline rate of ASMI was −0.021 (standard error (SE) 0.007) (95% CI: −0.034 to −0.007, p = 0.002), consistent with a 2.059% decrease of ASMI at 5-year follow-up relative to baseline. Subgroup analyses showed RA patients without sustained remission (−0.031 (SE 0.008) p = 0.0003, p for interaction = 0.022), and those with a total dose of glucocorticoids (equivalent dose of prednisone) >6052 mg (−0.050 (SE 0.017) p = 0.007, p for interaction = 0.049) have a higher annual decline rate of ASMI. There were 15.2% ( n = 32) patients who experienced a transition from non-myopenia to myopenia during the follow-up. The transition proportion of RA patients with sustained remission was significantly lower than that of patients without sustained remission (3.2% vs 20.3%, p = 0.002), and patients with a total dose of glucocorticoids >6052 mg showed a higher transition risk than those without (31.5% vs 11.7%, p = 0.008). Conclusion: Our findings firstly illustrated the annual decline rate of muscle mass in female RA patients from a 5-year longitudinal data, and revealed the potential effect of tight control of disease activity and less glucocorticoid use for delaying the loss of muscle mass.
Pan et al. (2026) studied this question.