Is education associated with mortality for breast cancer and cardiovascular disease among black and white women?

Abstract

Although low socioeconomic status (SES) has been found to be an important risk factor for all-cause mortality in women, the association is inconsistent across specific causes of death. SES appears to have different associations with 2 common causes of mortality in women: low SES is associated with greater cardiovascular disease (CVD) mortality in women but may also be associated with lower breast cancer mortality. We examined the association between SES and CVD and breast cancer mortality among black and white women. Our analysis sample included black and white women participating in the National Longitudinal Mortality Study, which links US Census Bureau Current Population Surveys with the National Death Index between 1979 and 1989. Education and income were used as SES indicators. For each cause of death, we used multivariate logistic regression to estimate variation in mortality risk across SES levels within each racial group. The sample included 21,303 black women and 186,322 white women. Unadjusted cumulative incidence (over a mean follow-up period of 8.7 years) of CVD mortality was 4.2% among black women and 2.3% among white women, and of breast cancer mortality was 0.3% among black women and 0.4% among white women. After adjustment for age, marital status, and urban or rural residence, less education was still associated with greater CVD mortality among black women (odds ratio [OR], 1.8; 95% Cl, 1.03-3.0) and white women (OR, 1.4; 95% Cl, 1.3-1.6). However, less than a high school education was associated with lower breast cancer mortality among white women (OR, 0.73; 95% CI, 0.6-0.9) but not among black women (OR, 1.1; 95% Cl, 0.5-2.3). Similar ORs were obtained when income was examined. The association between SES and cause-specific mortality may differ between black and white women for breast cancer death but not CVD death. Better understanding of these inter actions could guide the targeting of more effective interventions.