Muscle Mass, Strength, Mobility, Quality of Life, and Disease Severity in Ankylosing Spondylitis Patients: A Preliminary Study

OBJECTIVE: To determine if there is muscle mass reduction in patients with ankylosing spondylitis (AS) compared to the general population and to examine the relationship between skeletal muscle mass, quality of life (QOL), strength, and mobility in patients with AS. METHODS: A total of 30 AS patients were enrolled in this study. Skeletal muscle mass was measured by bioelectrical impedance analysis, and it was expressed as the skeletal muscle mass index (SMI). QOL was assessed using the EuroQOL (EQ-5D). To measure mobility, the modified Schöber test and chest expansion test were used. To measure grip strength as a measure of muscle strength, we used the hydraulic hand dynamometer. Additionally, we divided the patients into two groups according to the degree of X-ray finding and compared the differences between the two groups. RESULTS: There was no significant reduction in skeletal muscle mass in patients with AS compared to the general population. Also, there was no significant correlation between SMI and QOL. On the other hand, there was a significant positive correlation between SMI and mobility, and grip strength. A significant positive correlation was found between mobility and QOL. Additionally, there was a statistically significant difference in mobility between the two groups according to the degree of X-ray finding. CONCLUSION: Maintaining muscle mass in AS patients may not be helpful for improving QOL, but it may contribute to achieving adequate mobility and strength.