Nonalcoholic fatty liver disease incidence and impact on metabolic burden and death: A 20 year-community study

Recent population-based data on nonalcoholic fatty liver disease (NAFLD) epidemiology in general, and incidence in particular, are lacking. We examined trends in NAFLD incidence in a U.S. community and the impact of NAFLD on incident metabolic comorbidities (MCs), cardiovascular (CV) events, and mortality. A community cohort of all adults diagnosed with NAFLD in Olmsted County, Minnesota, between 1997 and 2014 was constructed using the Rochester Epidemiology Project database. The yearly incidence rate were calculated. The impact of NAFLD on incident MCs, CV events, and mortality was studied using a multistate model, with a 4:1 age- and sex-matched general population as a reference. We identified 3,869 NAFLD subjects (median age, 53; 52% women) and 15,209 controls; median follow-up was 7 (1-20) years. NAFLD incidence increased 5-fold, from 62 to 329 in 100,000 person-years. The increase was highest (7-fold) in young adults, aged 18-39 years. The 10-year mortality was higher in NAFLD subjects (10.2%) than controls (7.6%; P < 0.0001). NAFLD was an independent risk factor for incident MCs and death. Mortality risk decreased as the number of incident MCs increased: relative risk (RR) = 2.16 (95% confidence [CI], 1.41-3.31), 1.99 (95% CI, 1.48-2.66), 1.75 (95% CI, 1.42-2.14), and 1.08 (95% CI, 0.89-1.30) when 0, 1, 2, or 3 MCs were present, respectively. The NAFLD impact on CV events was significant only in subjects without MCs (RR = 1.96; 95% CI = 1.35-2.86). NAFLD reduced life expectancy by 4 years, with more time spent in high metabolic burden. Conclusion: Incidence of NAFLD diagnosis in the community has increased 5-fold, particularly in young adults. NAFLD is a consequence, but also a precursor of MC. Incident MC attenuates the impact of NAFLD on death and annuls its impact on CV disease. (Hepatology 2018;67:1726-1736).