Incidence of liver-related morbidity and mortality in a population cohort of non-alcoholic fatty liver disease.

Background & Aims: Non-alcoholic fatty liver disease (NAFLD) increases morbidity and mortality. However, patients in biopsy-based cohorts are highly selected and the absolute risks of liver- and non-liver outcomes in NAFLD in population remains undefined. We analysed both liver-related and non-liver-related outcomes in Finnish population cohorts of NAFLD.

Methods: We included 10 993 individuals (6707 men, mean age 53.3 ± 12.6 years) with NAFLD (fatty liver index ≥60) from the Finnish population-based FINRISK and Health 2000 studies. Liver fibrosis was assessed by the dAAR score, and genetic risk by a recent polygenic risk score (PRS-5). Incident liver-related outcomes, cardiovascular disease (CVD), cancer and chronic kidney disease (CKD) were identified through linkage with national registries.

Results: Mean follow-up was 12.1 years (1128 069 person-years). The crude incidence rate of liver-related outcomes in NAFLD was 0.97/1000 person-years. The cumulative incidence increased with age, being respectively 2.4% and 1.5% at 20 years in men and women aged 60 years at baseline, while the relative risks for CVD and cancer were 9-16 times higher. The risk of CKD exceeded that of liver outcomes at a baseline age around 50 years. 20-year cumulative incidence of liver-related outcomes was 4.3% in the high, and 1.5% in the low PRS-5 group. The dAAR score associated with liver outcomes, but not with extra-hepatic outcomes.

Conclusion: The absolute risk of liver-related outcomes in NAFLD is low, with much higher risk of CVD and cancer, emphasizing the need for more individualized and holistic risk-stratification in NAFLD.