Low-quality muscle mass rather than normal-quality muscle mass determines fibrosis progression in biopsy-proven NAFLD.

Abstract

Sarcopaenia is associated with advanced nonalcoholic fatty liver disease (NAFLD). However, the impact of the muscle mass categorised by muscle quality on fibrosis progression remains unclear. A total of 292 patients with biopsy-proven NAFLD who underwent serial vibration-controlled transient elastography assessments at least 1 year from baseline were selected. The skeletal muscle area (SMA) was determined on abdominal computed tomography (CT) at the third lumbar vertebra level and categorised to normal-attenuation muscle area (NAMA), low-attenuation muscle area (LAMA) and intermuscular adipose tissue (IMAT) using a muscle quality map. These SMAs were normalised by the height squared to obtain the skeletal muscle index (SMI). At baseline, as the histological fibrosis stage increased, SMINAMA decreased and SMILAMA increased (p for trend = 0.014 and p for trend <0.001, respectively), which was not significant after adjustment for age, sex and obesity. During a median follow-up of 41 months, fibrosis progression was detected in 48 out of 292 patients, and higher SMILAMA quartiles independently increased the risk of fibrosis progression in a dose-dependent manner (hazard ratio [HR] per quartile: 1.41; 95% confidence interval [CI], 1.04-1.91). The highest quartile of SMILAMA increased the risk of fibrosis progression by 3.25 times compared to the lowest quartile of SMILAMA (95% CI, 1.18-8.90). SMINAMA quartiles were not associated with the risk of fibrosis progression. Increased low-quality muscle mass, but not decreased normal-quality muscle mass, as assessed by a muscle quality map in CT, predicts fibrosis progression in patients with NAFLD.