Association of low skeletal muscle mass with advanced liver fibrosis in patients with non-alcoholic fatty liver disease

Background and Aim Although low skeletal muscle mass (LSMM) is known to increase the risk of non-alcoholic fatty liver disease (NAFLD), limited reports have described the relationship between LSMM and advanced fibrosis. Here, we investigated the association between LSMM and advanced liver fibrosis in NAFLD patients. Methods Fatty liver was diagnosed using ultrasound, and appendicular skeletal muscle mass (ASM) was measured using bioelectrical impedance analysis. LSMM was defined in two ways: ASM/body weight percentage (LSMM-BW) and ASM/body mass index. Liver fibrosis stage was assessed by two models, the NAFLD fibrosis score and the Fibrosis-4 index, which determined low and high cutoff values (COVs). Results Of 10 711 NAFLD patients, 615 were diagnosed with LSMM-BW. LSMM patients were older (47.6 vs 52.5 years, P = 0.001) and had higher body mass index values (23.6 vs 29.1 kg/m(2), P < 0.001) and waist circumferences (80.1 vs 93.3 cm, P < 0.001) than non-LSMM patients. LSMM was an independent risk factor for advanced fibrosis assessed by a low COV for the Fibrosis-4 index regardless of its classification (adjusted for metabolic and lipid profiles and sex, odds ratio [OR], 1.27-2.01; all P < 0.05). LSMM was an independent risk factor for advanced fibrosis assessed by both COVs of NAFLD fibrosis score (adjusted for obesity, hypertension, lipid profile, and sex; OR, 1.64-2.01, P < 0.01 in the low COV group; OR, 2.68-3.12, P = 0.002 in the high COV group). Conclusions Low skeletal muscle mass is associated with advanced fibrosis in NAFLD patients independent of metabolic risk factors.