Attributable Fractions of Nonalcoholic Fatty Liver Disease for Mortality in the United States: Results From the Third National Health and Nutrition Examination Survey With 27 Years of Follow-up

Background and aims: Nonalcoholic fatty liver disease (NAFLD) encompasses a range of conditions, from simple steatosis to nonalcoholic steatohepatitis. Studies in the United States have reported an increased mortality risk among individuals with NAFLD; therefore, the population attributable fractions (PAFs) for mortality were examined.

Approach and results: A total of 12,253 adult individuals with ultrasound assessment of NAFLD from the Third National Health and Nutrition Examination Survey and mortality follow-up through 2015 were included in the analysis. Cox proportional hazard regression was used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for NAFLD in association with all-cause and cause-specific mortality. Overall, sex- and race/ethnicity-specific PAFs and 95% CIs were estimated. In the current study, presence of NAFLD was associated with a 20% increased risk of all-cause mortality (HR, 1.20; 95% CI, 1.08, 1.34). The overall PAF for all-cause mortality associated with NAFLD was 7.5% (95% CI, 3.0, 12.0). The PAF for diabetes-specific mortality was 38.0% (95% CI, 13.1, 63.0) overall, 40.8% (95% CI, 2.1, 79.6) in men, and 36.8% (95% CI, 6.6, 67.0) in women. The PAF for liver disease (LD)-specific mortality was notably higher in men (68.3%; 95% CI, 36.3, 100.0) than women (3.5%; 95% CI, -39.7, 46.8). In the race-specific analysis, the PAFs of NAFLD for all-cause mortality (9.3%; 95% CI, 4.0, 14.6) and diabetes-specific mortality (44.4%; 95% CI, 10.8, 78.0) were significantly greater than zero only for whites.

Conclusions: In the United States, approximately 8% of all-cause mortality and more than one-third of LD- and diabetes-specific deaths are associated with NAFLD. With these high percentages, efforts are needed to reduce the burden of NAFLD in the United States.