Ethnic Differences in the Link Between Insulin Resistance and Elevated ALT

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) exhibits tight links with insulin resistance (IR) and the metabolic syndrome (MetS), a cluster of cardiovascular risk factors. Comparedwith non-Hispanic whites, non-Hispanic black adolescents have more IR but a lower prevalence of NAFLD and MetS. Our hypothesis was that IR would be a better predictor of alanine aminotransferase (ALT) elevations than is MetS among non-Hispanic blacks. METHODS:We analyzed data from 4124 adolescents aged 12 to 19 years in the 1999 to 2010 NHANES, using unexplained elevations in ALT (.30 U/L) to characterize presumed NAFLD and using a pediatric adaptation of the Adult Treatment Panel III definition of MetS. RESULTS: Prevalence of elevated ALT varied by race/ethnicity (Hispanics 13.7%, non-Hispanic white 8.6%, non-Hispanic blacks 5.4%, P , .0001). Among non-Hispanic whites and Hispanics, a classification of MetS performed well in identifying adolescents with elevated ALT (odds ratios [ORs] 9.53 and 5.56, respectively), as did MetS-related indices. However, among non-Hispanic blacks, the association between MetS and ALT elevations was smaller in magnitude and technically nonsignificant (OR = 3.24, P = .051). Furthermore, among non-Hispanic blacks, the presence of IR and elevated waist circumference performed more poorly at identifying ALT elevations (ORs 3.93 and 2.28, respectively: significantly smaller than ORs for non-Hispanic whites, P , .05), with triglyceride elevations being a better predictor (OR = 4.44). CONCLUSIONS: Non-Hispanic black adolescents exhibit a lower relationship between IR and elevated ALT, supporting racial/ethnic differences in the link between MetS and NAFLD. These data may have implications regarding triggers for screening for NAFLD among nonHispanic black adolescents, focusing particularly on those with triglyceride elevations. Pediatrics 2013;132:e718–e726 AUTHORS: Mark D. DeBoer, MD, MSc, MCR,a R. Constance Wiener, DMD,b Barrett H. Barnes, MD,a and Matthew J. Gurka, PhDc aDepartment of Pediatrics, University of Virginia, Charlottesville, Virginia; and Departments of bDental Practice and Rural Health and cBiostatistics, School of Public Health, West Virginia University, Morgantown, West Virginia