Age, body mass index, and function as the independent predictors of sarcopenia in axial spondyloarthritis: a cross-sectional analysis

Sarcopenia is characterized by a decline in muscle strength, muscle mass, and physical performance. Persistent inflammation may lead to muscle wasting. This research aims to determine the prevalence and associated factors of sarcopenia in axial spondyloarthritis (ax-SpA). A cross-sectional study of 104 ax-SpA patients who met the 2009 ASAS criteria was conducted at Phramongkutklao Hospital between January 2020 and February 2021. Sarcopenia-related factors and disease characteristics were recorded. Sarcopenia was diagnosed according to the Asian Working Group for Sarcopenia 2019. Appendicular skeletal muscle mass was measured by dual-energy X-ray absorptiometry. Strength, ambulation, rising from a chair, stair climbing and history of falling (SARC-F) was evaluated. Muscle strength was measured by hand grip strength and chair stand time. Physical performance was assessed by 6-m walk and time up and go tests. Logistic regression was performed to identify factors associated with sarcopenia. Most patients were male (74%), with a mean (standard deviation, SD) age and disease duration of 42.6 (12.2) and 8.3 (8.5) years, respectively. The mean BMI (SD) was 23.8 (4.4). The prevalence of sarcopenia was 22.1%. There were no differences in disease activity (BASDAI and ASDAS) between ax-SpA patients with and without sarcopenia. Age, low BMI, and BASFI score were independently associated with sarcopenia, with adjusted odds ratios and 95% confidence intervals of 1.08 (1.01–1.16), 0.39 (0.25–0.63), and 1.41 (1.07–1.86), respectively. Sarcopenia is common in ax-SpA patients and is independently associated with older age, low BMI, and high BASFI score but not disease activity.