Introduction This study investigated whether treatment with biological/targeted synthetic disease–modifying antirheumatic drug (b/tsDMARD) affects muscle mass and phase angle in patients with rheumatoid arthritis (RA). Additionally, whether these improvements were a direct effect of the b/tsDMARD treatment, an indirect effect mediated by improved disease activity and glucocorticoid reduction, or both was clarified. Methods Data from 104 weeks of a prospective study comparing b/tsDMARD (n = 76) and conventional synthetic disease–modifying antirheumatic drug (csDMARD) treatments (n = 71) on body composition in RA patients were used. The phase angle measured using bioelectrical impedance analysis was used to evaluate muscle quality. Changes in body composition, including phase angle, were compared between the groups. We also examined the results using the mode of action. Parallel mediation analysis was used to investigate the effects of the b/tsDMARD treatment. Results Baseline median age and disease duration were 69.0 and 4.5 years, respectively. Changes (Δ) in muscle mass and phase angle were significantly higher in the b/tsDMARD group than the csDMARD group (0.4 kg vs. − 0.3 kg: p < 0.001 and 0.02° vs. − 0.06°: p = 0.047, respectively). There were no significant differences in the change in muscle mass or phase angle when examined using the mode of action. On parallel mediation analysis, the b/tsDMARD usage showed a significant direct effect on Δmuscle mass and Δphase angle (p = 0.012 and p = 0.047, respectively). Indirect effects via ΔDAS28-ESR (p = 0.510 and p = 0.695, respectively) and Δglucocorticoid dosage (p = 0.816 and p = 0.552, respectively) were not statistically significant. Conclusions Treatment with b/tsDMARD improved muscle mass and phase angle by blocking inflammatory cytokines and JAK-STAT signaling. <Table Float="No" ID="Taba"> <tgroup cols="2"> <colspec align="left" colname="c1" colnum="1" /> <colspec align="left" colname="c2" colnum="2" /> <tbody> <row> <entry align="left" nameend="c2" namest="c1"> Key Points • This study is the first to report that b/tsDMARD treatment is effective not only for increasing muscle mass but also for improving phase angle. • These effects appear to be primarily direct, rather than mediated through disease activity improvement or glucocorticoid reduction. • There were no significant differences in muscle mass gain or phase angle improvement when examined using the mode of action. </entry> </row> </tbody> </tgroup> </Table>

Biological/targeted synthetic disease–modifying antirheumatic drugs improve not only muscle mass but also phase angle in patients with rheumatoid arthritis

期刊论文
发表日期：

2025年10月31日

查看全文

Masahiro Tada,
Yoshinari Matsumoto,
Tatsuya Koike,
Kenji Mamoto,
Tomoyuki Nakamura,
Shohei Anno,
Takahiro Iida,
Hitoshi Goto,
Masanori Matsuura

摘要

Introduction

This study investigated whether treatment with biological/targeted synthetic disease–modifying antirheumatic drug (b/tsDMARD) affects muscle mass and phase angle in patients with rheumatoid arthritis (RA). Additionally, whether these improvements were a direct effect of the b/tsDMARD treatment, an indirect effect mediated by improved disease activity and glucocorticoid reduction, or both was clarified.

Methods

Data from 104 weeks of a prospective study comparing b/tsDMARD (n = 76) and conventional synthetic disease–modifying antirheumatic drug (csDMARD) treatments (n = 71) on body composition in RA patients were used. The phase angle measured using bioelectrical impedance analysis was used to evaluate muscle quality. Changes in body composition, including phase angle, were compared between the groups. We also examined the results using the mode of action. Parallel mediation analysis was used to investigate the effects of the b/tsDMARD treatment.

Results

Baseline median age and disease duration were 69.0 and 4.5 years, respectively. Changes (Δ) in muscle mass and phase angle were significantly higher in the b/tsDMARD group than the csDMARD group (0.4 kg vs. − 0.3 kg: p < 0.001 and 0.02° vs. − 0.06°: p = 0.047, respectively). There were no significant differences in the change in muscle mass or phase angle when examined using the mode of action. On parallel mediation analysis, the b/tsDMARD usage showed a significant direct effect on Δmuscle mass and Δphase angle (p = 0.012 and p = 0.047, respectively). Indirect effects via ΔDAS28-ESR (p = 0.510 and p = 0.695, respectively) and Δglucocorticoid dosage (p = 0.816 and p = 0.552, respectively) were not statistically significant.

Conclusions

Treatment with b/tsDMARD improved muscle mass and phase angle by blocking inflammatory cytokines and JAK-STAT signaling.

Key Points

• This study is the first to report that b/tsDMARD treatment is effective not only for increasing muscle mass but also for improving phase angle.

• These effects appear to be primarily direct, rather than mediated through disease activity improvement or glucocorticoid reduction.

• There were no significant differences in muscle mass gain or phase angle improvement when examined using the mode of action.