Socioeconomic status (SES), traditionally assessed by income, education, and occupation, reflects individuals’ material and social resources. Various theories of social stratification emphasize different aspects of SES and suggest different types of measurement. However, virtually all measures of SES are related to morbidity and mortality, suggesting that SES is a pervasive and robust influence on health.
What is the Association of Socioeconomic Status and Health?
In industrialized countries, SES is related to health at all levels of the socioeconomic hierarchy. It is not simply that those in poverty experience poorer health than those with more income; even individuals well above the poverty level have poorer health than those who are relatively more affluent. At an individual level, the health burden of socioeconomic disadvantage is most acute for the very poorest. At a population level, because a far greater proportion of people are in the middle of the SES distribution than at the extremes, a substantial proportion of health effects related to socioeconomic factors occur to those who are not in extreme poverty. Although the association of SES and health extends to the top of the SES hierarchy, for some health outcomes (e.g., infant mortality), the association is stronger at the bottom than at the top. Thus, although health benefits still accrue as SES improves to the very top, the marginal benefits of higher SES may diminish at upper levels.
The monotonic relationship of socioeconomic status and health has been demonstrated with each of the main components of SES. With regard to occupation, the Whitehall Studies of British civil servants found that higher occupational grade was associated with lower mortality, not only when comparing the lowest grade civil servants to the highest, but also when comparing midlevel civil servants to those at the highest levels. As noted, studies of income also reveal lower mortality as income increases, although there is a steeper drop in mortality associated with increasing income among those with the least income. Benefits of education also accrue to health not simply from high school graduation, but also from college graduation and from graduate degrees, although these benefits may not be equally enjoyed by men and women and by all racial/ethnic groups.
Given the association of SES with mortality, it is not surprising that SES is also related to morbidity. Incidence and prevalence of most diseases increase as SES decreases. The association is especially strong for cardiovascular disease, arthritis, diabetes, chronic respiratory diseases, and cervical cancer.
Incidence of mental diseases is also greater among lower-SES populations. Among the mental diseases, SES is most closely associated with schizophrenia, substance use, and anxiety disorders. There are a few diseases that show the opposite pattern and are more common among higher-SES individuals. Most notable are breast cancer and malignant melanoma. These associations are partially accounted for by SES-related differences in risk-related behaviors: delayed childbearing with regard to breast cancer and recreational tanning with regard to melanoma.
What Accounts for the Association of Socioeconomic Status and Health?
There is no single factor accounting for the association of SES and health. Several pathways have been identified, and are summarized in the following subsections.
Lower-SES individuals are subject to a range of health-damaging conditions. Less affluent populations have greater exposure to adverse living conditions including crowding, poor sanitation, peeling paint, substandard housing, proximity to dump sites, and greater air pollution. The environmental justice movement has raised awareness of such differential exposure. Environmental justice has been adopted by governmental agencies, including the Environmental Protection Agency, and has led to policy and zoning reform to assure a more equal burden of environmental risk.
Physical exposures also occur in the workplace. Lower-SES occupations more often involve manual labor, which may place workers at risk for injury and involve greater exposure to toxins. Material conditions, such as car and house ownership, have also been linked to better health, and appear to make an independent contribution to morbidity and mortality above and beyond the standard SES measures.
Access to Health Care
Those who are poorer, unemployed, and less educated are less likely to have access to high-quality health care. In the United States, private health insurance is tied to employment, and a substantial segment of the population is uninsured. The uninsured have less access to preventive services, screening and early diagnosis, and high-quality care. Even among those who have access to the same system of health care (e.g., members of health maintenance organizations), lower SES continues to be linked to poorer health outcomes. Knowledge of how to utilize the health system to get higher-quality care (which is likely to be greater among those with more education) may play a role in this association. However, it may also be due to conditions outside of the health care system linked to SES that are affecting outcomes.
Health behaviors are estimated to be responsible for more than 40% of premature mortality. Behaviors that are most responsible for premature mortality are smoking, sedentary lifestyle, poor diet, sexual risk behaviors, and substance use. Rates of these health-risking behaviors increase the lower one’s income, education, and/or occupational status. For example, 52% of men with less than a high school education smoke cigarettes, compared to 43% of high school graduates and 29% of college graduates.
In addition to behavioral contributions to the onset of disease, SES-related behaviors may affect the course of disease. Treatment for many diseases and conditions requires close adherence to prescribed regimens. For example, the course of diabetes is greatly affected by dietary intake and monitoring of blood glucose. Diabetics with less education have been found to show poorer adherence, and differences in adherence largely account for the association of education and course of disease. Similar findings emerge with regard to adherence to antiretroviral therapy among HIV-positive patients.
Higher SES is associated with greater protection from adverse health effects of stress. Both acute and chronic stress are reported more frequently among those lower on the SES hierarchy. Possessing more resources, whether from higher education, income, or occupational status, may help people avoid situations that are stressful and also help them cope more effectively with those that they do encounter. It is easier to engage in active coping strategies, which are generally associated with better health, when one has more resources with which to address threatening situations. The wear and tear on the body of responding to more frequent and chronic exposures to stress heightens the risk of dysregulation of the hypothalamic-pituitary-adrenal axis, which is central to the stress response and to the development of disease.
More-threatening and adverse environments associated with lower SES may engender psychological responses that increase the risk of disease. Hostility, anger, optimism/pessimism, sense of control, and social support, all of which are associated with disease risk, are also related to SES. Though few studies have directly tested whether these psychological variables mediate the impact of SES on disease, there are numerous studies showing that they are related on one hand to SES and on the other hand to disease risk.
Health Affects Socioeconomic Status
Although the predominant causal direction appears to be from SES to health, health may also affect SES. Individuals who are in poorer health may be less likely to achieve higher SES status. Children from poorer families are reported by their parents to have worse health. Poorer health in childhood can contribute to missed school and lower achievement. The impact of health on educational attainment is likely to be greatest from diseases that have their onset during childhood and adolescence (e.g., asthma, schizophrenia). In later life, those who become ill may be less likely to be able to work, which affects their income and occupational status.
How Does Socioeconomic Status Relate to Race/Ethnicity and Gender?
People of color in the United States generally have poorer health status than do White Americans. For example, compared to Whites, African-Americans have poorer overall health and higher rates of HIV/AIDS, diabetes, heart disease, cancer, and stroke For some conditions, racial/ethnic group differences become nonsignificant once socioeconomic factors (e.g., income) is controlled for. For other conditions, racial/ethnic group differences remain even after controlling for SES. These findings suggest that to some extent racial/ethnic health disparities are due to socioeconomic disadvantage, but that unique experiences associated with minority status (e.g., experiences of discrimination, residential segregation) also play a role. Associations of SES with health differ by gender as well as by race and ethnicity. The meaning of a given SES indicator may vary for men versus women and for Whites versus people of color, which suggests the importance of looking at SES influences on health within each group.
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