MRI-AST (MAST) Score Accurately Predicts Major Adverse Liver Outcome, Hepatocellular Carcinoma, Liver Transplant, and Liver-Related Death

Abstract

Background & aims: The MRI-AST (MAST) score accurately identifies patients with at-risk nonalcoholic steatohepatitis, defined as nonalcoholic steatohepatitis with nonalcoholic fatty liver disease activity score ≥4 and fibrosis stage ≥2 at highest risk for disease progression. It is important to determine the robustness of the MAST score in predicting major adverse liver outcomes (MALO), hepatocellular carcinoma (HCC), liver transplant, and death.

Methods: This retrospective analysis included patients with nonalcoholic fatty liver disease from a tertiary care center who underwent magnetic resonance imaging proton density fat fraction, magnetic resonance elastography, and laboratory testing within 6 months from 2013 to 2022. Other causes of chronic liver disease were excluded. Hazard ratios between logit MAST and MALO (ascites, hepatic encephalopathy, or bleeding esophageal varices), liver transplant, HCC, or liver-related death were computed using a Cox proportional hazards regression model. We computed the hazard ratio of MALO or death associated with MAST scores 0.165-0.242 and 0.242-1.000, using MAST scores 0.000-0.165 as the reference group.

Results: Among 346 total patients, average age was 58.8 years with 52.9% females and 34.4% with type 2 diabetes. Average alanine aminotransferase was 50.7 IU/L (24.3-60.0 IU/L), aspartate aminotransferase was 38.05 IU/L (22.00-41.00 IU/L), platelets were 242.9 × 10⁹/L (193.8-290.0 × 10⁹/L), proton density fat fraction was 12.90% (5.90%-18.22%), and liver stiffness on magnetic resonance elastography was 2.75 kPa (2.07-2.90 kPa). Median follow-up was 29.5 months. Fourteen had adverse outcomes, including 10 MALO, 1 HCC, 1 liver transplant, and 2 liver-related deaths. The Cox regression of MAST versus adverse event rate had a hazard ratio of 2.01 (95% confidence interval, 1.59-2.54; P < .0001) for each 1 logit unit increases in MAST. The corresponding Harrell concordance statistic (C statistic) was 0.919 (95% confidence interval, 0.865-0.953). The MAST score ranges of 0.165-0.242 and 0.242-1.0, respectively, had adverse event rate hazard ratio of 7.75 (1.40-42.9; P = .0189) and 22.11 (6.59-74.2; P < .0000) relative to MAST 0-0.165.

Conclusions: The MAST score noninvasively identifies at-risk nonalcoholic steatohepatitis and accurately predicts MALO, HCC, liver transplant, and liver-related death.

Keywords: Fatty Liver; Liver Outcomes; MAST Score; NAFLD.