Allostatic Load Burden and Racial Disparities in Mortality

Abstract

Black-white disparities in mortality persist after adjustment for socioeconomic status and health behaviors. We examined whether allostatic load, the physiological profile influenced by repeated or chronic life stressors, is associated with black-white mortality disparities independent of traditional sociobehavioral risk factors. We studied 4515 blacks and whites aged 35 to 64 years from the third National Health and Nutrition Examination Survey (1988-1994), using the linked mortality file, to ascertain participant deaths through 2006. We estimated unadjusted sex-specific black-white disparities in cardiovascular/diabetes-related mortality and noninjury mortality. We constructed baseline allostatic load scores based on 10 biomarkers and examined attenuation of mortality disparities in 4 sets of sex-stratified multivariate models, sequentially adding risk factors: (1) age/clinical conditions, (2) socioeconomic status (SES) variables, (3) health behaviors, and (4) allostatic load. Blacks had higher allostatic load scores than whites; for men, 2.5 vs 2.1, p < .01; and women, 2.6 vs 1.9, p < .01. For cardiovascular/diabetes-related mortality among women, the magnitude of the disparity after adjustment for other risk factors (hazard ratio [HR], 1.63; 95% confidence interval [CI], 0.96-2.75) decreased after adjustment for allostatic load (HR, 1.15; 95% CI, 0.70-1.88). For noninjury mortality among women, the magnitude of the disparity after adjustment for other risk factors (HR, 1.43; 95% CI, 1.00-2.04) also decreased after adjustment for allostatic load (HR, 1.26; 95% CI, 0.90-1.78). For men, disparities were attenuated but persisted after adjustment for allostatic load. Allostatic load burden partially explains higher mortality among blacks, independent of SES and health behaviors. These findings underscore the importance of chronic physiologic stressors as a negative influence on the health and lifespan of blacks in the United States.