Association between Relative Skeletal Muscle Mass and Metabolic Dysfunction-Associated Steatotic Liver Disease Development in a Community-Based Population.

Background: This study explores how relative skeletal muscle mass is associated with the development of metabolic dysfunction-associated steatotic liver disease (MASLD) and the remission of baseline MASLD in a community-based population cohort. Methods: The study included 1,544 participants with an average age of 58 years. All participants underwent baseline and follow-up assessments in 2015 or 2016. Appendicular skeletal muscle mass was measured using an automatic bioelectrical impedance analysis (BIA), and total skeletal muscle mass was calculated using the BIA equation. Relative skeletal muscle mass was evaluated in two ways: divided by weight and divided by visceral fat area (VFA). Liver fat content was assessed using ultrasonography, and the NAFLD fibrosis score was calculated to quantify the degree of liver fibrosis. Results: During a median follow-up of 2.1 years, each one-standard deviation increase in relative total skeletal muscle mass was associated with a decreased risk of MASLD incidence among males (hazard ratio [HR], 0.56; 95% confidence interval [CI], 0.43 to 0.74, adjusted for weight; and HR, 0.23; 95% CI, 0.13 to 0.42, adjusted for VFA) and females (HR, 0.62; 95% CI, 0.47 to 0.83, adjusted for weight; and HR, 0.37; 95% CI, 0.19 to 0.70, adjusted for VFA). In both sexes, the increase in relative appendicular skeletal muscle mass was also associated with a reduced MASLD risk. We found statistically significant inverse associations between relative skeletal muscle mass and both liver fat content and liver fibrosis. Conclusion: Low relative muscle mass is associated with an increased risk of MASLD incidence and persistence. Therefore, increasing skeletal muscle mass over time might aid in the prevention and management of MASLD.