Race and ethnicity: vital constructs for diabetes research.

M edical researchers are now paying increasing attention to findings of racial or ethnic (“racial/ethnic” hereafter) differences in quality and access to care, health outcomes, risk factors, genetic markers, and therapeutic response. However, this attention has been met with growing controversy and debate. Society’s history of discrimination, racism and eugenics, and continued disparities in access and quality of care make this a particularly sensitive issue. In the past year, the New England Journal of Medicine (1–4) and the International Journal of Epidemiology (5,6) have published several commentaries and editorials, some criticizing and others arguing in favor of the use of race/ethnicity in medical research. The editorial board of the Archives of Pediatric and Adolescent Medicine recently instructed submitting authors not to detail race/ethnic variation in disease or risk factors unless there is proof of the biologic, scientific, or sociologic bases for these differences (7). While social epidemiologists have justifiably criticized some molecular scientists’ espousing “genetic-determinism,” many social epidemiologists have promoted the equally unsubstantiated perspective that dismisses the influence of genetics on racial disparities in disease (5). At the heart of this controversy is a dispute about whether studying the construct of race/ethnicity has any justification in medical research at all. Concerns of the sociologic risks associated with doing racial/ethnicity research [e.g., stigmatization and emphasis on differences rather than similarities and racial profiling in choice of therapy (2)] have also been raised. Epidemiological research on race/ethnicity, however, has a long history of apparent utility, facilitating the identification of subgroups with higher rates of disease (8) and differing levels of risk factors (9) and the detection of disparities in the quality of and access to care (10,11) and differing response to pharmacotherapy (12), and providing potentially important leads about etiology and the roles of genes and environment (13,14). This debate has now reached the diabetes scientific community as well; this year’s American Diabetes Association Scientific Sessions (June 2003) dedicated a special session to debate the use and measurement of race/ethnicity in diabetes research. Given that there are few disease states that demonstrate such marked racial/ethnic variation as diabetes, this discussion has particular relevance for diabetes research. During the calendar year 2002, 6% of the articles published in Diabetes Care focused on race/ethnicity (i.e., included the words “race,” “racial,” “ethnic,” or “ethnicity” in the title or abstract). In this issue of Diabetes Care, de Rekeneire et al. (14a) report on variability in glycemic control by race/ethnicity in the Health, Aging, and Body Composition Study cohort. In the U.S., poorer glycemic control among African-American and Latino patients has been reported from several cross-sectional population-based samples (15–17), the National Health and Nutrition Examination Survey, 1988 – 1994 (NHANES-3) (18), the Behavioral Risk Factor Surveillance Survey (BRFSS) (19), the Insulin Resistance and Atherosclerosis Study (IRAS) (20), and the Translating Research Into Action for Diabetes (TRIAD) study (Dr. Arleen Brown, submitted for publication). There are numerous other examples of race/ethnic disparities specific to diabetes, including the prevalence of diabetes (21), diabetesrelated complications (8), risk factors (22), and quality of diabetes care (11). Given the growing controversy, researchers need to be aware of the particular issues and methodologies and to develop a critical eye when evaluating and planning studies of racial/ethnic differences in disease outcomes, risk factors, and health services. Included below is a commentary on the recent debate about the value of race/ethnicity in medical research and a brief review of select methodological issues. [For more comprehensive and excellent discussions regarding methodological issues, see articles by Lin and Kelsey (14) and Risch et al. (13).] There is a growing recognition of the importance of race/ethnicity in our research activities, and National Institutes of Health now requires documentation of minority inclusion on all new grant submissions (23). However, some scientists suggest that there is insufficient evidence that race/ethnicity has biological or genetic significance (3,6,24–27) and promote ignoring race/ethnicity in medical research altogether. Justification of this so-called “race-neutral approach” rests largely on two contentions. First, race/ ethnicity is strictly a social construct and too crudely measured to have value in public health. Second, race/ethnicity is not a biological construct because there is more intra-individual genetic variation within a race than between races. Eric Lander popularized this concept with what is known as the “99.9% identical rule,” which states that “any two human beings on this Earth are 99.9% identical at the DNA level” (28). However proponents often fail to mention that although individuals are genotypically almost identical, the 10th of a percent of the genome’s 3 billion letters that are different translates into roughly 3 million sequence differences, with some conferring dramatically differing risk of disease (e.g., cystic fibrosis or sickle cell disease). Thus, it has been argued that failing to design studies to accommodate the contingencies for interactions between populations and genes, important population differ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●