SAFETY Study: Alanine Aminotransferase Cutoff Values Are Set Too High for Reliable Detection of Pediatric Chronic Liver Disease

Abstract

Background & Aims The appropriate alanine aminotransferase (ALT) threshold value to use for diagnosis of chronic liver disease in children is unknown. We sought to develop sex-specific, biology-based, pediatric ALT thresholds. Methods The screening ALT for elevation in today’s youth (SAFETY) study collected observational data from acute care children’s hospitals, the national health and nutrition examination survey (NHANES, 1999–2006), overweight children with and without non-alcoholic fatty liver disease (NAFLD), and children with chronic Hepatitis B virus (HBV) or Hepatitis C virus (HCV) infections. The study compared the sensitivity and specificity of ALT thresholds currently used by children’s hospitals versus study-derived, sex-specific, biology-based, ALT thresholds for detecting children with NAFLD, HCV, or HBV. Results The median upper limit of ALT at children’s hospitals was 53 U/L (range, 30–90). The 95th percentile levels for ALT in healthy weight, metabolically normal, liver disease-free, NHANES pediatric participants were 25.8 U/L (boys) and 22.1 U/L (girls). The concordance statistics of these NHANES-derived thresholds for liver disease detection were 0.85 (95% confidence interval [CI] 0.74–0.96) in boys and 0.91 (95% CI 0.83–0.99) in girls for NAFLD, 0.80 (95% CI 0.70–0.91) in boys and 0.79 (95% CI 0.69–0.89) in girls for HBV, and 0.86 (95% CI 0.77–0.95) in boys and 0.84 (95% CI 0.75–0.93) in girls for HCV. Using current children’s hospitals ALT thresholds, the median sensitivity for detection of NAFLD, HBV, and HCV ranged from 32% to 48%; median specificity was 92% (boys) and 96% (girls). Using NHANES-derived thresholds, the sensitivities were 72% (boys) and 82% (girls); specificities were 79% (boys) and 85% (girls). Conclusions The upper limit of ALT used in children’s hospitals varies widely and is set too high to reliably detect chronic liver disease. Biology-based thresholds provide higher sensitivity and only slightly less specificity. Clinical guidelines for use of screening ALT and exclusion criteria for clinical trials should be modified.