Increased Mortality Among Lean Versus Non-Lean Adults With MASLD: A Multicenter Study

Background and Aim: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a leading cause of chronic liver disease worldwide. Since the adoption of the new terminology from the Delphi Consensus statement, there has not been a large multicenter cohort study of MASLD among lean versus non-lean individuals. This study aims to assess prevalence and incidence outcomes among lean and non-lean individuals with MASLD in a diverse patient cohort. Methods: We conducted a retrospective multicenter study on patients with MASLD at the Banner and the University of Michigan Health systems from 2012 to 2023. Main outcomes included mortality and incidence of cirrhosis, cardiovascular disease (CVD), major adverse liver outcome (MALO), and cancer. Results: Seventy-five thousand nine hundred twenty-one patients were included in this cohort with 5% lean individuals. In this cohort, 4.99% were lean, 23.16% were overweight, 28.47% were obesity class I, and 43.39% were obesity class II–III; 58.49% were female; and 66.32% were non-Hispanic White, 22.23% Hispanic, 4.75% Black, 1.71% Native Americans (NAs), and 1.97% Asian/Pacific Islander. After adjusting for confounders, lean individuals had a higher mortality, higher incidence of CVD, and higher incidence of MALO. Conclusions: Lean individuals have a higher mortality, higher cardiovascular burden, and higher incidence of MALO compared to non-lean individuals. Further studies are warranted to explore lean patients with MASLD, and interventions are needed to decrease mortality in this patient population.