AIM To investigate the relationship between nonalcoholic fatty liver disease (NAFLD) and cardiovascular events among a nationally representative sample of young adults in Korea.

METHODS AND RESULTS This population-based cohort study from the Korean National Health Insurance Service included adults who were aged 20 to 39 years when they underwent a health examination between 2009 and 2012. NAFLD was defined as a fatty liver index (FLI) ≥60, and participants were divided into three groups according to FLI (<30, 30-59 and ≥60) to investigate the dose-dependent effect of FLI score. Among 5 324 410 participants, 9.8% had an FLI ≥60. There were 13 051 myocardial infarctions (MIs; 0.39%) and 8573 strokes (0.26%) during a median follow-up of 8.4 years. In multivariable analysis, NAFLD was associated with a higher risk of MI and stroke (hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.61-1.77 and HR 1.73, 95% CI 1.63-1.84, respectively). MI and stroke had dose-dependent relationships with FLI (HR 1.28 in participants with FLI 30-59 and 1.73 in those with FLI ≥60 for MI and HR 1.18 in participants with FLI 30-59 and 1.41 in those with FLI ≥60 for stroke, respectively).

CONCLUSIONS Nonalcholic fatty liver disease was an independent predictor of MI and stroke in young adults. These results suggest that primary prevention of cardiovascular disease should be emphasized in young adults with NAFLD.