Socioeconomic Status,Race, and Mortality: A Prospective Cohort Study

Objectives. We evaluated the independent and joint effects of race, individual socioeconomic status (SES), and neighborhood SES on mortality risk.Methods. We conducted a prospective analysis involving 52 965 non-Hispanic Black and 23 592 non-Hispanic White adults taking part in the Southern Community Cohort Study. Cox proportional hazards modeling was used to determine associations of race and SES with all-cause and cause-specific mortality.Results. In our cohort, wherein Blacks and Whites had similar individual SES, Blacks were less likely than Whites to die during the follow-up period (hazard ratio HR] = 0.78; 95% confidence interval CI] = 0.73, 0.84). Low household income was a strong predictor of all-cause mortality among both Blacks and Whites (HR = 1.76; 95% CI = 1.45, 2.12). Being in the lowest (vs highest) category with respect to both individual and neighborhood SES was associated with a nearly 3-fold increase in all-cause mortality risk (HR = 2.76; 95% CI = 1.99, 3.84). There was no significant mortality-related interaction between individual SES and neighborhood SES among either Blacks or Whites.Conclusions. SES is a strong predictor of premature mortality, and the independent associations of individual SES and neighborhood SES with mortality risk are similar for Blacks and Whites.From birth through approximately age 85 years, there is a mortality rate disparity between Blacks and Whites in the United States that peaks in early adulthood and slowly narrows thereafter.1–4 Most of the excess deaths among Blacks occur in middle-aged adults, given the confluence of rising mortality rates and the disparity at those ages. During much of the 20th century, this disparity was unyielding,4–6 but recent data point to some narrowing of the gap beginning in the 1990s.7–9 Still, in 2011 the highest age-standardized death rate in the United States was that among non-Hispanic Blacks (877.4 per 100 000 standard population), followed by non-Hispanic Whites (738.1 per 100 000 standard population).10 Also, average life expectancies at birth in 2011 were 4.5 years shorter for Black than White men and 3.1 years shorter for Black than White women.10Although national mortality data are routinely reported by race/ethnicity, their interpretation must consider the determinants of race-specific mortality rates, including behavioral, social, economic, and political factors that determine the resources available to maintain health and prolong life.3 Whether socioeconomic status (SES) completely accounts for mortality differences between Blacks and Whites is not clear. Previous studies have reported that SES alone cannot fully account for the disparity, although in settings where Blacks and Whites are drawn from considerably different SES strata, confounding by SES may be difficult to overcome.11–14 By contrast, in settings where race-specific SES differences are minimal (including the current study), it has been suggested that important health indicators are quite similar by race.15–17 Individual-level SES aside, neighborhood-level SES has also been reported to influence mortality rates,18 but fewer investigations have assessed the joint contribution of individual and neighborhood SES,19–22 and analyses assessing the interplay of these 2 SES domains with race are rare.19,21We thus took the opportunity, within a large prospective study of non-Hispanic Black and White adults (residing in a large area of the United States, enrolled mainly in low-income settings but also non-low-income settings, and representing a range of SES levels), to evaluate the independent and joint contributions of race, individual SES, and neighborhood SES to overall and cause-specific mortality risk.