External validation of biomarkers of fatty liver in the general population: the Bagnacavallo study

Objective: We externally validated the fatty liver index (FLI), the lipid accumulation product (LAP), the hepatic steatosis index (HSI), and the Zhejiang University index (ZJU) for the diagnosis of fatty liver (FL) and non-alcoholic fatty liver disease (NAFLD) in the general population. Subjects and Methods: The validation was performed on 2159 citizens of the town of Bagnacavallo (Ravenna, Italy). Calibration was evaluated by calculating the calibration slope and intercept and by inspecting calibration plots; discrimination was evaluated using the c-statistic. Results: The average calibration slope was 1 and the average intercept was 0 for all combinations of outcomes and biomarkers. As for FL, the c-statistic was 0.85 for FLI, 0.83 for ZJU, 0.82 for HSI, and 0.80 for LAP. As for NAFLD, the c-statistic was 0.77 for FLI, 0.76 for ZJU, 0.75 for HSI, and 0.74 for LAP. All the biomarkers were strongly correlated with each other. Conclusion: FLI, LAP, HSI, and ZJU can be used to diagnose FL in the Bagnacavallo population, even if FLI has the highest discriminative ability. The same biomarkers perform similarly for the diagnosis of NAFLD even if FLI has a small advantage as discrimination is concerned.