Optimal Cutoffs of Fatty Liver Index and Hepatic Steatosis Index in Diagnosing Pediatric Metabolic Dysfunction-associated Steatotic Liver Disease

Abstract

BACKGROUND & AIMS: Despite the high global prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD), effective noninvasive diagnostic tools in pediatric populations remain limited. We aimed to validate the predictive performance of the fatty liver index (FLI) and hepatic steatosis index (HSI) in diagnosing MASLD in the young population and propose optimal cutoff points for the diagnosis of MASLD and severe MASLD. METHODS: This cross-sectional study included data from 1158 and 203 youths from the United States National Health and Nutrition Examination Survey (NHANES) 2017 to 2020 and real-world clinical environments, respectively. Hepatic steatosis was defined based on controlled attenuation parameter values obtained from vibration-controlled transient elastography or ultrasonography. The performances of the FLI and HSI were evaluated using logistic regression, the area under the receiver operating characteristic curve (AUC), and optimal cutoffs determined via Youden's index. RESULTS: The AUCs of FLI and HSI for MASLD were 0.91 and 0.90 in the NHANES data, respectively, and 0.93 for both indices in real-world clinical data. The optimal cutoffs for MASLD diagnosis were 20 (lower) and 50 (upper) for the FLI and 30 (lower) and 40 (upper) for the HSI. For severe MASLD, the FLI cutoff increased to 60, whereas the HSI cutoff remained at 40, with both achieving AUCs of 0.83. In youth with normal alanine aminotransferase levels, the AUCs of both indices were 0.89 in the NHANES and 0.91 in real-world clinical data. CONCLUSIONS: FLI and HSI are effective noninvasive tools for diagnosing pediatric MASLD and severe MASLD, including in youth with normal alanine aminotransferase levels.