Metabolic dysfunction-associated steatotic liver disease is associated with the risk of severe liver fibrosis in pediatric population.

Metabolic dysfunction-associated steatotic liver disease (MASLD) has been proposed to replace the term of non-alcoholic fatty liver disease (NAFLD). To investigate the effect of MASLD on liver fibrosis and validate the clinical utility of MASLD criteria, differences in disease severity and clinical outcomes between MASLD and NAFLD were compared in a biopsy-proven pediatric cohort. The retrospective clinical data of 427 children with biopsy-proven steatotic liver between 2010 and 2021 were consecutively collected and categorized into three distinct subgroups of MASLD-only, NAFLD-only, and MASLD-NAFLD according to the diagnostic guidelines. Patients with MASLD-only and MASLD-NAFLD had more features of metabolic disorders, with higher level of triglycerides but lower level of high-density lipoprotein cholesterol than NAFLD-only. The proportion of significant fibrosis was highest in MASLD-only patients (68.0%), followed by those with MASLD-NAFLD and NAFLD-only (43.3% and 19.4%, respectively; P < 0.001). More steatohepatitis was presented in MASLD-NAFLD group than the other two groups (66.1% vs 30.8% vs 22.6%, P < 0.001). Multivariate regression revealed that children with MASLD-only had 5.8-fold greater risk of significant fibrosis than those with NAFLD-only (P = 0.001). After a median follow-up of 83 months, 14 of 427 patients developed clinical outcomes. Kaplan-Meier curves indicated no difference in the cumulative incidence of clinical events between the groups (log-rank, P = 0.073). Children in MASLD group tended to have concomitant with severe liver fibrosis and related metabolic diseases compared to those with NAFLD-only in pediatric cohort. Thus, the redefinition of MASLD may improve the detection of children with severe disease that need early intervention.