Relationship between the locomotive syndrome and skeletal muscle mass index in patients with rheumatoid arthritis

Abstract

Objective: This study aimed to investigate the association between locomotive syndrome（LS）and skeletal muscle mass index（SMI）in patients with rheumatoid arthritis（RA）.

Methods: A total of 160 RA patients attending rheumatology outpatient clinics were included in this study. LS was defined as a scoring ≥16 points on the 25-question Geriatric Locomotive Function Scale. SMI was measured using bioelectrical impedance analysis（Inbody-S10;Tanita Corp, Tokyo, Japan）. Low-SMI was defined as <7.0kg/m² in men and <5.7kg/m² in women.

Results: Among all the RA patients, the prevalence of LS was 38.0%, with a significantly higher occurrence in older individuals. The mean SMI was 7.2 ± 0.9kg/m² in men and 5.6 ± 0.9kg/m² in women. The proportion of individuals with low-SMI was 55%. There was no significant difference in SMI between the LS and non-LS groups, and the prevalence of LS was 39% in the normal-SMI groups. When comparing patients with and without LS, the following factors were found to be statistically significant: indoor activities, activities of daily living（ADL）, mental health status.

Conclusions: In RA patients, reduced participation in indoor activities, ADL and mental health status were associated with an increased risk of LS. Although SMI was not affected, dynapenia led to decreased motor function.