Abstract Body: Background: Epigenetic age acceleration (EAA), the difference between DNA methylation-calculated age (DNAmAge) and chronological age, reflects biological aging. However, few studies have examined the prospective association of EAA with mortality in a national-representative sample. This study aims to investigate whether EAA is predictive of all-cause and cardiovascular disease (CVD) specific mortality over 20-year follow-up in the National Health and Nutrition Examination Survey (NHANES, cycle 1999–2002).
Methods: We included 2,353 participants aged over 50 who had DNA methylation data at baseline and have been linked to the National Death Index in 2019. EAA was calculated by regressing DNAmAge on age and cell composition, using six estimators (Horvath, Hannum, SkinBlood, PhenoAge, GrimAgeMort, GrimAge2Mort). CVD deaths were identified by specific ICD-10 codes. Survival month was defined as the interval between baseline and the time of death or censorship. Cox proportional hazards models, adjusted for demographics, socioeconomic status, smoking, BMI, and chronic diseases, were used. Analyses were stratified by pre-existing CVD and BMI.
Results: Over a median follow-up of 207 months, 1,210 deaths (385 CVD-specific) occurred. All EAA measures were significantly associated with increased all-cause mortality (except for SkinBlood-EAA) and CVD-specific mortality (except for Horvath-EAA). For instance, per 5-year increment of Hannum-EAA was associated with a 13% higher risk of all-cause mortality (HR: 1.13, 95% CI: 1.07 – 1.21), and 25% higher risk of CVD-specific mortality (HR: 1.25, 95% CI: 1.12 – 1.40). In those with pre-existing CVD, all EAA measures (excluding Horvath-EAA) were significantly associated with CVD mortality (e.g., PhenoAge-EAA HR: 1.13, 95% CI: 1.02–1.24), while no significant associations were found for participants without pre-existing CVD (e.g., Hannum-EAA HR: 1.08, 95% CI: 0.88–1.32). Stratified by BMI, obese individuals showed the highest hazard ratios. For instance, Hannum-EAA in obese participants was associated with an HR of 1.17 (95% CI: 1.04–1.32), compared to normal-weight (HR: 1.12, 95% CI: 1.00–1.25) and overweight participants (HR: 1.06, 95% CI: 0.95–1.18).
Conclusion: Accelerated biological aging, as indicated by epigenetic clocks, was associated with increased all-cause and CVD-specific mortality risk in a US representative sample over 20 years. Associations were stronger among those with pre-existing CVD or obesity.