Noninvasive Assessment of Nonalcoholic Fatty Liver Disease in Obese or Overweight Patients

BACKGROUND & AIMS: Reliable noninvasive tools are needed for staging nonalcoholic fatty liver disease (NAFLD). Published scoring systems have not been validated in prospective assessments of unselected patients. We aimed to identify factors that predicted development of nonalcoholic steatohepatitis (NASH) in a large group of overweight or obese patients and compared these with established factors. METHODS: We performed a prospective analysis of factors associated with the development and severity of NAFLD in patients at a single obesity center. We evaluated liver involvement in 542 patients by a large set of routine and non-routine parameters, including ultrasound and genetic testing. Those suspected of having NAFLD underwent liver biopsy (57.7%). Patients were divided into design cohort (n = 200) and validation cohort (n = 113) to identify factors associated with the presence and severity of NAFLD and NASH. RESULTS: Factors independently associated with development of NASH included increased levels of alanine aminotransferase (ALT), fasting levels of C-peptide, and ultrasound steatosis scores (USSs), with area under the receiver operating curve (AUROC) values of 0.854 in the design cohort and 0.823 in the validation cohort. NASH activity scores also correlated with level of ALT, USS, and fasting level of C-peptide (R-2 = 0.491). Independent predictors of advanced fibrosis included waist circumference and level of aspartate aminotransferase (AUROC values of 0.839 and 0.846 for design and validation cohorts, respectively; negative predictive values of 98% and 97%, respectively, for a cutoff of -2.14). Previously published scoring systems had significantly lower AUROC values. Levels of CK18 and PNPLA3 polymorphisms correlated with development of NASH but did not add value. CONCLUSIONS: Parameters routinely analyzed in assessing obese patients can be used to determine the presence of NASH and advanced fibrosis. Non-routine tests do not increase diagnostic accuracy. Previously published scores are significantly less accurate.