The association of fatty liver index and metabolic syndrome with cardiovascular outcomes, liver-related mortality, and all-cause mortality: a nationwide cohort study.

We investigated the risk of cardiovascular events, all-cause mortality, and liver-related mortality according to the presence of metabolic syndrome (MetS) and fatty liver index (FLI). In this retrospective longitudinal population-based cohort study, we used Korean National Health Insurance Service data from 2009 to 2012. Nonalcoholic fatty liver disease (NAFLD) was defined as FLI ≥ 60. Risk of all-cause mortality, liver-related mortality, and major adverse cardiovascular events (MACE) including myocardial infarction (MI), stroke, heart failure (HF), and cardiovascular disease (CVD)-related mortality was assessed according to the presence of MetS and FLI among adults (aged 40 to 80 years) who underwent health examinations (n = 769,422). During a median 8.59 years of follow up, 44,356 (5.8%) cases of MACE, 24,429 (3.2%) cases of all-cause mortality, and 1114 (0.1%) cases of liver-related mortality were detected in the entire cohort. When the FLI < 30 without MetS group was set as a reference, the FLI ≥ 60 with MetS group had the highest risk of MACE (adjusted hazard ratio [aHR] 2.05, 95% confidence interval [CI] 1.98-2.13) and all-cause mortality (aHR 1.96, 95% CI 1.86-2.07). The risk of liver-related mortality (aHR 10.71, 95% CI 8.05-14.25) was highest in the FLI ≥ 60 without MetS group. The FLI ≥ 60 with MetS group had a higher risk of MACE (aHR 1.39, 95%CI 1.28-1.51), a lower risk of liver-related mortality (aHR 0.44, 95%CI 0.33-0.59), and no significant difference in all-cause mortality compared with the FLI ≥ 60 without MetS group. The FLI ≥ 60 with MetS group was associated with the highest risk of MACE and the FLI ≥ 60 without MetS group had the highest risk liver-related mortality, but there was no significant difference in all-cause mortality between two groups. In conclusion, as FLI levels increase, the risk of MACE increases, and the risk increases additively in the presence of MetS. The risk of liver-related mortality increases with higher FLI levels, the effect of high FLI on increased risk is more significant in groups without MetS compared to those with MetS.