Dallas Steatosis Index Identifies Patients With Nonalcoholic Fatty Liver Disease

Abstract

Background & aims: Tools have been developed to determine risk for nonalcoholic fatty liver disease (NAFLD) based on imaging, which does not always detect early-grade hepatic steatosis. We aimed to develop a tool to identify patients with NAFLD using ¹H MR spectroscopy (MRS).

Methods: We collected data from the Dallas Heart Study-a multiethnic, population-based, probability study of adults (18-65 y) that comprised an in-home medical survey; collection of fasting blood samples; MRS images to measure cardiac mass/function, abdominal subcutaneous/visceral adiposity; and quantification of hepatic triglyceride concentration, from 2000 through 2009. NAFLD were defined as 5.5% or more liver fat and we excluded patients with more than moderate alcohol use; 737 patients were included in the final analysis. We performed binary multivariable logistic regression analysis to develop a tool to identify patients with NAFLD and evaluate interactions among variables. We performed an internal validation analysis using 10-fold cross validation.

Results: We developed the Dallas Steatosis Index (DSI) to identify patients with NAFLD based on level of alanine aminotransferase, body mass index, age, sex, levels of triglycerides and glucose, diabetes, hypertension, and ethnicity. The DSI discriminated between patients with vs without NAFLD with a C-statistic of 0.824. The DSI outperformed 4 risk analysis tools, based on net reclassification improvement and decision curve analysis.

Conclusions: We developed an index, called the DSI, which accurately identifies patients with NAFLD based on MRS data. The DSI requires external validation, but might be used in development NAFLD screening programs, in monitoring progression of hepatic steatosis, and in epidemiology studies.

Keywords: Detection; Diagnostic; MRI; Prognostic Factor.