Linear age-course association between non-alcoholic fatty liver disease, components of metabolic syndrome, and mortality

BackgroundThe study aimed to explore the relationship between non-alcoholic fatty liver disease (NAFLD) and mortality by age and metabolic syndrome (MetS) components. MethodWe enrolled 104,173 participants in the Kailuan cohort from June 2006 through October 2013. Cox regression models were used to evaluate the hazard ratio (HR) and 95% confidence interval (CI). Population-attributable fractions (PAFs) of metabolic components were also calculated. ResultsCompared with non-NAFLD, the excess risk of all-cause and cardiovascular disease (CVD)-related mortality in NAFLD increased with the number of MetS components but decreased with age. The highest all-cause and CVD-related death risks were observed in NAFLD aged 18-39 with 4-5 MetS (HR=2.81, 95% CI:1.55-5.08) and those aged 40-49 years with 3 MetS (HR=2.25, 95% CI:1.55-5.08), respectively. However, there was no significant extra risk of liver-related death in NAFLD patients of any age. For PAF, 28.5% of all-cause and 43.4% of CVD-related mortality among NAFLD patients was preventable by controlling MetS components < 2, with the highest PAF in those aged 50-69 and 18-49, respectively. Elevated blood pressure (PAF of 24.7% for all-cause; 38.6% for CVD-related), elevated fasting glucose (PAF of 13.4% all-cause; 9.2% CVD-related), and elevated triglycerides (PAF of 3.9% all-cause; 14.0% CVD-related) were the essential mortality contributors in NAFLD participants. ConclusionThe excess risk of all-cause and CVD-related mortality in NAFLD patients decreases with age. A substantial proportion of risks could be averted if NAFLD patients are controlled under two MetS components, especially managing blood pressure, fasting glucose, and triglycerides for the young.