Longitudinal Course of Muscle Status in Patients With Rheumatoid Arthritis
Toshifumi Fujiwara1, Hidetoshi Tsushima1, Osamu Tokunaga1
1Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Fukuoka Prefecture, Japan.
International Journal of Rheumatic Diseases
|August 3, 2026
Summary
Muscle impairment is common in rheumatoid arthritis (RA) patients, often persisting over time. Older age and lower body mass index (BMI) are linked to this condition.
Area of Science:
- Rheumatology
- Geriatrics
- Muscle Physiology
Background:
- Rheumatoid arthritis (RA) frequently causes muscle impairment, yet longitudinal data on its progression are scarce.
- Understanding the prevalence and course of muscle impairment in RA is crucial for patient management.
Purpose of the Study:
- To determine the prevalence of muscle impairment in RA patients.
- To analyze longitudinal changes in muscle status over approximately 29 months.
- To identify factors associated with muscle impairment in RA.
Main Methods:
- Retrospective cohort study of 75 RA patients.
- Skeletal Muscle Mass Index (SMI) and handgrip strength assessed using bioelectrical impedance analysis.
- Muscle status classified using Asian Working Group for Sarcopenia 2025 criteria; muscle impairment defined as low muscle mass, possible sarcopenia, or sarcopenia.
Main Results:
- High baseline prevalence of muscle impairment (73.3%), with 40% having sarcopenia.
- Muscle impairment associated with older age, lower BMI, advanced RA stage, poorer physical function, and reduced quality of life.
- Older age (OR 1.10) and lower BMI (OR 0.79) independently predicted muscle impairment.
- No significant longitudinal changes in SMI or handgrip strength observed; most patients maintained their baseline muscle status.
Conclusions:
- Muscle impairment is highly prevalent and persistent in established RA.
- Older age and lower BMI are key independent factors associated with muscle impairment in RA.
- Findings highlight the chronic nature of muscle impairment in RA patients, emphasizing the need for targeted interventions.
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