BMI Metrics Are Poor Predictors of Pediatric Nonalcoholic Fatty Liver Disease Severity.

Background: Alternative BMI metrics are superior to BMI z score (BMI z ) in tracking obesity but have not been evaluated in patients with nonalcoholic fatty liver disease (NAFLD). Our objective was to evaluate whether BMI-adjusted z score (BMI az ) or BMI expressed as a percentage of the 95th percentile (%BMIp95) are better predictors of degree of alanine aminotransferase (ALT) elevation, a surrogate for NAFLD severity, compared with BMI z in patients with NAFLD. Methods: A retrospective study of 776 subjects aged 2-18 years with BMI z  > 1.0 followed in a NAFLD subspecialty clinic was conducted. Regression analysis was used to determine predictors of elevated ALT. Results: There was no association between BMI z , BMI az , or %BMIp95 and degree of ALT elevation using linear or logistic regression. Conclusion: These results do not support the use of alternative BMI metrics for evaluating NAFLD severity. Future studies should investigate longitudinal assessments and correlation with histology.