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Racial differences in mortality: Beyond socioeconomic status

Black older adults in the U.S have higher mortality rates than white older adults, and according to many studies, socioeconomic status (SES) accounts for a large part of this disparity. But little is known about the simultaneous effect of SES, psychosocial, behavioral, and health factors in explaining the racial differences.

Now, a large study has examined numerous, specific factors—economic, psychosocial, behavioral, health-related, and insurance-related—that might play a role in racial differences in mortality among older people. The findings suggest that risk factors go beyond traditional measures of SES and, in some cases, include lack of supplemental (medigap) health insurance and behavioral factors. The study also found that race-related risk factors for mortality, such as SES, may differ depending on the underlying cause of death.

“Our findings suggest that it is important to consider different SES measures from those traditionally used in research,” said Roland J. Thorpe, Ph.D., at the Hopkins Center for Health Disparities Solutions, part of the Johns Hopkins Bloomberg School of Public Health. When examining race differences among older adults in future studies, he said, “we should start to more frequently examine SES measures such as educational quality, financial strain, and wealth in addition to the traditional education and income measures.”

Published in the February 2012 issue of Annals of Behavioral Medicine, the study included 2,938 black and white men and women in their 70s, all well-functioning and living independently in the community at the beginning of the study. The participants were part of an ongoing longitudinal cohort study, the Dynamics of Health, Aging and Body Composition (Health ABC), at NIA.

Delving into details

For the mortality study, Dr. Thorpe and his colleagues collected data from each participant not only on income and educational level—traditional SES measures—but also on financial assets, perceived financial inadequacy, and functional literacy level. Psychosocial factors included living arrangements, social contact, emotional support, perception of personal mastery (the belief that one has the ability to control outcomes), and religious faith. Participants were asked to report if they had insurance in addition to Medicare and if they smoked or drank alcohol. They indicated their level of physical activity and rated their own health as excellent/very good, fair, or poor. Baseline data were also collected on a wide range of diseases and conditions, cognitive functioning, and depressive symptoms.

Over the 8 years of this study, 17 percent of the whites and 24 percent of the blacks died. Looking at deaths from all causes, SES accounted for 60 percent of the difference between the races, while behavioral factors and self-rated health, considered separately, each explained about 30 percent of the difference. When the researchers simultaneously accounted for the different measures of SES, health insurance, psychosocial, behavioral, and health-related factors, and self-rated health, black and white participants had a similar risk of all-cause mortality.

Heart disease and cancer deaths

The investigators also looked at deaths due specifically to coronary heart disease (CHD) and cancer. Blacks had a higher risk of CHD mortality. SES explained 96 percent of the difference. Health-related factors, behavioral factors, and self-rated health, when considered separately, each explained over 40%. Again, when accounting for all factors simultaneously, black and white participants’ risk of CHD mortality was similar.

For cancer–related mortality, blacks also had a higher risk, but in contrast to CHD-related mortality, only 30 percent of the racial difference was explained by SES. Health insurance accounted for 18 percent and behavioral factors for 17 percent. When looking at all factors simultaneously, black participants’ risk of dying from cancer remained somewhat higher than that of whites.

The authors note that different types of cancer have different causes, further complicating the relationship between SES and cancer. One of their conclusions is that race-related risk factors for mortality may differ by the underlying cause of death. Among blacks, for instance, risk factors for death from CHD may differ from risk factors for a specific cancer. The authors recommend that future research focus on understanding how various race-related risk factors contribute to such disease-specific mortality differences.

Other findings have implications for public health policy. White participants in the study had a higher prevalence of cancer, but blacks had higher cancer death rates, a finding that was associated with blacks’ lower rate of supplemental health insurance.

"This is important,” said Dr. Thorpe. “It suggests that improved access to health care may help reduce disparities in cancer-related mortality.”