Muscle fat contents rather than muscle mass determines nonalcoholic steatohepatitis and liver fibrosis in patients with severe obesity.

OBJECTIVE

This study aimed to investigate the association of muscle fat contents, nonalcoholic steatohepatitis (NASH), and liver fibrosis in patients with severe obesity.

METHODS

Patients with severe obesity who underwent bariatric surgery were evaluated for NASH and liver fibrosis. Skeletal muscle was assessed by dual energy x-ray absorptiometry, and muscle fat contents (skeletal muscle fat index [SMFI]) were evaluated by computed tomography-based psoas muscle mass and density.

RESULTS

A total of 104 patients with severe obesity were enrolled (57 with nonalcoholic fatty liver disease activity score <5 and 47 with NASH with nonalcoholic fatty liver disease activity score ≥5). SMFI was higher in patients with NASH than those without NASH (mean [SD], 39.0 [14.5] vs. 46.5 [14.2] for without NASH vs. with NASH; p = 0.009). SMFI was also correlated with hepatic steatosis grade, ballooning severity, and fibrosis stage. Multiple logistic regression analysis showed that SMFI was associated with higher risk of NASH and liver fibrosis (odds ratio = 2.37, 95% CI: 1.13-4.98, p = 0.022 for NASH; odds ratio = 2.93, 95% CI: 1.32-6.48, p = 0.008 for significant liver fibrosis).

CONCLUSIONS

Muscle fat infiltration rather than muscle mass reflects the severities of hepatic steatosis and fibrosis in patients with severe obesity.