Allen AM, et al. - Researchers carried out this study to investigate trends in nonalcoholic fatty liver disease (NAFLD) incidence in a US community, and the effect of NAFLD on incident metabolic comorbidities (MC), cardiovascular (CV) events and mortality. In the community, the incidence of NAFLD diagnosis had increased 5-fold, especially in young adults. NAFLD was a consequence but also a precursor of MC. Incident MC attenuated the effect of NAFLD on death and nullified its impact on CV disease.

• The researchers constructed a community cohort of all adults diagnosed with NAFLD in Olmsted County, MN between 1997-2014 using the Rochester Epidemiology Project database.  
• They calculated the yearly incidence rate.
• Using a multi-state model, the impact of NAFLD on incident MC, CV events and mortality was studied, with a 4:1 age and sex-matched general population as reference.

• A total of 3,869 NAFLD subjects (median age 53, 52% women) and 15,209 controls were identified.
• Median follow-up was 7 (1 to 20) years.
• From 62 to 329/100,000 person-years, NAFLD incidence increased 5-fold.
• In young adults (18-39 years), the increase was highest (7-fold).
• In NAFLD subjects (10.2%), the 10-year mortality was higher than controls (7.6%) (p<0.0001).
• An independent risk factor for incident MC and death was NAFLD.
• As the number of incident MC increased, mortality risk decreased: RR= 2.16 (95% 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 MC were present, respectively.
• Only in subjects without MC, the NAFLD impact on CV events was significant (RR=1.96, 95% CI=1.35-2.86).
• With more time spent in high metabolic burden, NAFLD reduced life expectancy by 4 years.