Are racial disparities in health conditional on socioeconomic status?
Introduction
Inequalities in health status between white and black persons have been a major concern for both scientists and public health officials, especially in the United States. The health problems of black people are substantial and manifest over the life course (Farley, 1984; Ferraro & Farmer, 1996a). Black people generally report higher levels of morbidity, and this difference is pronounced for illnesses such as diabetes and hypertension (Otten, Teutsch, Williamson, & Marks, 1990; Reed, Darity, & Roberson, 1993). Moreover, black people manifest the highest mortality rate for heart disease, stroke and many types of cancer (Centers for Disease Control, 2002; Keppel, Pearcy, & Wagener, 2002; National Center for Health Statistics, 2003). Black adults also suffer from more functional disability (Freid, Prager, MacKay, & Xia, 2003; Kelly Moore & Ferraro, 2004), and are more likely to rate their health negatively (Ferraro, Farmer, & Wybraniec, 1997; Hughes & Thomas, 1998; Mutchler & Burr, 1991).
A major explanation for the racial health inequality focuses on socioeconomic status (SES). Black people traditionally have a lower education level than whites (Newburger & Curry, 2000), have higher unemployed rates than white adults (Thomas & Hughes, 1986), and are more likely to experience poverty at all ages (Johnson, 1994; McKinnon 2003). Research also provides overwhelming evidence that SES influences patterns of morbidity, function and mortality (Appel, Harrell, & Deng, 2002; Berkman & Gurland, 1998; Winkleby & Cubbin, 2003). The compelling evidence regarding SES differences in health has led some scholars to conjecture years ago that health differences between black and white adults would shrink appreciably, perhaps even disappear, if SES differences were eradicated (e.g., Jackson, 1985; Markides & Mindel, 1987).
Research on racial health disparities has generally moved beyond debates about whether it is race or class that influences outcomes. As argued by Willie (1979), race and class are not identical or interchangeable and, therefore, a change in one does not necessarily lead to a change in the other. As Navarro (1991, p. 341) states, “The issue is not race or class. The issue is race and class.” Rather, there is a growing recognition that question is not race or class, but how race and class operate—as main effects or conditionally (Collins, 2000; Pappas, 1994; Pettigrew, 1981; Wilson, 1980). Stated differently, are the health benefits of higher SES different for black and white people? If yes, then the relationship is conditional or interactive. To date however, much of the literature on racial differences in health status does not utilize the interaction approach to examine conditional effects; most studies routinely examine only the main effects of race and SES.
The research presented here examines racial disparities in health and gives explicit attention to the possibility of an interaction between race and SES on health. Using a 20-year longitudinal framework, both morbidity and self-rated health are considered as health outcomes. To capture the multifaceted phenomena of SES, multiple individual-level indicators including education, income, occupational prestige, and employment status were used to operationalize SES. The goals of this research are two-fold: (1) to examine if black Americans experience poorer health than white Americans over the 20 year period and (2) to utilize the interaction approach to test for conditional relationships between race and SES on health.
Section snippets
Race and SES
Although it is clear that black adults are not experiencing the same level of health as white adults, there is inconsistency in the literature about the effect of SES on eliminating the racial gap in health status. Many studies report that despite controlling for SES, racial differences persist in morbidity (Ferraro & Farmer, 1996a; Winkleby, Kraemer, Ahn, & Varady, 1998), functional impairment/disability (Clark & Maddox, 1992; Ferraro & Farmer, 1996a), and self-rated health, well being, or
Data
This research used longitudinal data from the nationally representative sample of the National Health and Nutrition Examination Survey I (NHANES): Epidemiologic Follow-up Study (NHEFS). The sampling design was a multistage, stratified, probability sample of adults age 25–74 who were not institutionalized at the baseline interview, 1971–1975 (see National Center for Health Statistics et al., 1987, for details). A subsample at baseline (N=6931, white Americans=5968, black Americans=873) was
Findings
Means and standard deviations for all variables are presented for the total sample and subsamples by race in Table 1. Black Americans reported significantly more serious illness and poorer self-rated health than white Americans at all waves. Reports of chronic illness were not significantly different by race at baseline or wave 2, but black adults reported significantly more chronic illness at the final wave. Black Americans were more likely to report restricted activity at baseline and more
Discussion
This research examined two basic questions: (1) Is there a racial gap in morbidity and self-rated health over 20 years? (2) If yes, are the racial differences conditional on SES? Regarding the first question, the results show that black adults began the study in poorer health: they were much more likely to suffer from serious illness and to rate their health poorly. In the examination of incident chronic and serious illness, the rate of change in morbidity over the 20 years was similar for
Acknowledgements
Support for this research was provided by the Purdue Research Foundation and the National Institute of Aging (AG11705). An earlier version of this paper was presented at the Annual Meeting of the American Sociological Association, Chicago, 1999. The data utilized in this paper were made available by the Inter-University Consortium for Political and Social Research. Neither the collector of the original data nor the Consortium bears any responsibility for the analyses or interpretations
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