Racial/ethnic disparities in all-cause mortality in U.S. adults: the effect of allostatic load

Abstract

Objective: We investigated the association between a cumulative biological risk or allostatic score and all-cause mortality risk. We used 13,715 records of participants aged 25 years and older from the Third National Health and Nutrition Examination Survey (NHANES III) linked to the National Death Index.

Methods: We specified all-cause mortality using the underlying cause of death in the death certificate. We calculated time to death from interview date through December 31, 2000, as person-years of follow-up using the NHANES III interview month and year. We used Cox proportional hazards regression to estimate hazard ratios (HRs) relating all-cause mortality risk for those with an allostatic score of 2 and > or = 3 relative to those with an allostatic score of < or = 1.

Results: After controlling for age, gender, race/ethnicity, education, and income, mortality rates were 40% (HR = 1.40, 95% confidence interval [CI] 1.11, 1.76) and 88% (HR = 1.88, 95% CI 1.56, 2.26) higher for participants with an allostatic score of 2 and > or = 3, respectively, compared with those with a score of < or = 1. The death rate associated with allostatic score for each racial/ethnic group differed with age.

Conclusions: The allostatic score increased the risk of all-cause mortality. Moreover, this increased risk was observed for adults younger than 65 years of age regardless of their race/ethnicity. Thus, allostatic score may be a contributor to premature death in the U.S.