The Fatty liver Index (FLI) 15 years later: a reappraisal

Abstract The Fatty Liver Index (FLI) is a non-invasive biomarker proposed, in 2006, by Bedogni’s group, to aid in identifying patients with suspected nonalcoholic fatty liver disease (NAFLD) to be submitted to liver ultrasonography to confirm steatosis. Criteria of Assessment of Narrative Review Articles, a scale for the assessment of quality of narrative review articles, inspired our review article, which aims at evaluating the scope of published articles on FLI issued over the last 15-year period. The analysis of retrieved data identified the following conclusions. First, given that FLI and NAFLD share the same risk factors, FLI can be used to identify NAFLD among populations at risk to be submitted to screening. Second, FLI is able to identify the hazard of atherosclerosis, both at a subclinical stage and as an overt disease. Third, FLI detects incident diabetes and chronic kidney disease. However, evidence supporting the notion that FLI also predicts the metabolic syndrome, some endocrine disorders, certain tumor types, and overall and cause-specific mortality appears to be more limited. In conclusion, 15 years after its first publication, FLI has been validated as a robust biomarker of both steatosis and NAFLD. Moreover, the scope of FLI has been expanded to previously unexpected areas. Finally, we discuss FLI limitations and a research agenda aimed at further improving the accuracy of FLI scores in predicting liver-related outcomes, endocrine-metabolic disorders, cancer risk, and survival.