David R. Williams, PhD, MPH, professor of sociology at the University of Michigan Institute for Social Research, Ann Arbor, Mich., studied the relationship between socioeconomic status (SES) and health.
Using the Panel Study of Income Dynamics (PSID), an ongoing longitudinal survey of U.S. households begun in 1968 with mortality follow-up through 1992, Williams and his colleagues examined how aspects of SES—such as income, occupation, gender, and race—affect health status and predict mortality.
His research team also analyzed data from the Detroit Area Study (DAS) conducted in 1995 and the Americans' Changing Lives (ACL) longitudinal survey begun in 1986 and repeated in 1989 and 1994.
The project was part of the Robert Wood Johnson Foundation (RWJF) national program Investigator Awards in Health Policy Research.
The research resulted in the publication of a series of articles in which Williams observes:
- Racial differences in health are markedly, but not wholly, explained by income.
- Perceived discrimination and race-related stress also play a role.
- Persistent low income can be an especially good predictor of mortality regardless of race.
- Contrary to popular opinion, when income is taken into account, behavioral risk factors such as smoking, alcohol drinking, sedentary lifestyle, and obesity accounted for only a small proportion of differences in mortality across sex, race, and age groups.
In an article in the Journal of Health Psychology, Williams and colleagues state that:
- Education and especially income matter most to health status, but discrimination and stress play an incremental role.
In an article in the American Journal of Public Health, Williams and colleagues write that:
- While income loss had the greatest impact on mortality among middle-income individuals, persistent poverty was the strongest predictor among low-income persons.
In a study published in the Journal of the American Medical Association (JAMA), the researchers found that:
- Persons with incomes of less than $10,000 were 3.22 times more likely to die of any cause than were those with incomes over $30,000.
- Because income is so important a determinant of health disparities among people of different races, Williams concludes that policies to reduce income differentials, especially to raise incomes in the lowest tier, would provide the most help in dealing with these differences.