Utility of a New Model to Diagnose an Alcohol Basis for Steatohepatitis

Background & Aims: Distinguishing an alcohol basis from a nonalcoholic basis for the clinical and histologic spectrum of steatohepatitic liver disease is difficult because of unreliability of alcohol consumption history. Unfortunately, various biomarkers have had limited utility in distinguishing alcoholic liver disease (ALD) from nonalcoholic fatty liver disease (NAFLD). Thus, the aim of our study was to create and validate a model to diagnose ALD in patients with steatohepatitis. Methods: A cross-sectional cohort study was performed at the Mayo Clinic, Rochester, Minnesota, to create a model using multivariable logistic regression analysis. This model was validated in 3 independent data sets comprising patients of varying severity of steatohepatitis spanning over 10 years. Results: Logistic regression identified mean corpuscular volume, aspartate aminotransferase (AST)/alanine aminotransfersase (ALT) ratio, body mass index, and gender as the most important variables that separated patients with ALD from NAFLD. These variables were used to generate the ALD/NAFLD Index (ANI), with ANI of greater than zero incrementally favoring ALD and ANI of less than zero incrementally favoring a diagnosis of NAFLD, thus making ALD unlikely. ANI had a c-statistic of 0.989 in the derivation sample, and 0.974, 0.989, 0.767 in the 3 validation samples. ANI performance characteristics were significantly better than several conventional and recently proposed biomarkers used to differentiate ALD from NAFLD, including the histopathologic marker protein tyrosine phosphatase 1b, AST/ALT ratio, γ-glutamyl transferase, and carbohydrate-deficient transferrin. Conclusions: ANI, derived from easily available objective variables, accurately differentiates ALD from NAFLD in hospitalized, ambulatory, and pretransplantation patients and compares favorably with other traditional and proposed biomarkers.