The NAFLD Decompensation Risk Score: External Validation and Comparison to Existing Models to Predict Hepatic Events in a Retrospective Cohort Study

Abstract

The NAFLD decompensation risk score (the Iowa Model) was recently developed to identify patients with nonalcoholic fatty liver disease (NAFLD) at highest risk of developing hepatic events using three variables-age, platelet count, and diabetes. We performed an external validation of the Iowa Model and compared it to existing non-invasive models. We included 249 patients with NAFLD at Boston Medical Center, Boston, Massachusetts, in the external validation cohort and 949 patients in the combined internal/external validation cohort. The primary outcome was the development of hepatic events (ascites, hepatic encephalopathy, esophageal or gastric varices, or hepatocellular carcinoma). We used Cox proportional hazards to analyze the ability of the Iowa Model to predict hepatic events in the external validation (https://uihc.org/non-alcoholic-fatty-liver-disease-decompensation-risk-score-calculator). We compared the performance of the Iowa Model to the AST-to-platelet ratio index (APRI), NAFLD fibrosis score (NFS), and the FIB-4 index in the combined cohort. The Iowa Model significantly predicted the development of hepatic events with hazard ratio of 2.5 [95% confidence interval (CI) 1.7-3.9, P < 0.001] and area under the receiver operating characteristic curve (AUROC) of 0.87 (CI 0.83-0.91). The AUROC of the Iowa Model (0.88, CI: 0.85-0.92) was comparable to the FIB-4 index (0.87, CI: 0.83-0.91) and higher than NFS (0.66, CI: 0.63-0.69) and APRI (0.76, CI: 0.73-0.79). In an urban, racially and ethnically diverse population, the Iowa Model performed well to identify NAFLD patients at higher risk for liver-related complications. The model provides the individual probability of developing hepatic events and identifies patients in need of early intervention.