Independent and joint associations of fatty liver index and physical activity with mortality in adults with hypertension: a nationwide cohort study

Hypertension and non-alcoholic fatty liver disease (NAFLD) frequently coexist and share metabolic pathways that elevate cardiovascular and all-cause mortality risk. Although physical activity (PA) is known to reduce cardiovascular risk, its impact among individuals with both hypertension and NAFLD remains unclear. This nationwide cohort study examined the independent and joint associations of PA and fatty liver burden with mortality in adults with hypertension. We analyzed 139,015 individuals aged ≥ 20 years who participated in the Korean National Health Insurance Service health screening program between 2009 and 2012 and were followed through 2021. Fatty liver burden was assessed using the Fatty Liver Index (FLI) and categorized as < 30, 30-59, or ≥ 60. PA levels were self-reported and classified as < 500, 500-999, and ≥ 1000 MET-min/week. Over a median follow-up of 9.1 years, 12,281 deaths occurred, including 2013 from cardiovascular causes. Higher FLI (≥ 60) was associated with significantly increased all-cause (HR 1.35, 95% CI 1.26-1.44) and cardiovascular mortality (HR 1.32, 95% CI 1.12-1.56). In contrast, higher PA (≥ 1000 MET-min/week) was consistently associated with lower mortality across all FLI categories, with the strongest benefit among those with FLI < 30 (HR 0.51 for all-cause mortality and 0.49 for CVD mortality). Importantly, high PA levels remained protective even in individuals with severe fatty liver burden. These findings suggest that regular PA substantially reduces mortality risk in adults with hypertension, regardless of underlying fatty liver severity. PA promotion should be considered an essential strategy in managing hypertension and related metabolic dysfunction.