The role of race in science and medicine has been a longstanding topic of debate (1), with some arguing that racial and ethnic categories are clinically useful because they serve as a proxy for underlying population genetics. Others argue that the use of race in medicine is flawed, as race is a sociopolitical construct that cannot be used to accurately delineate distinct biological or physiological categories. It is unsurprising that this topic is highly polarized because the concept of race itself is based on cultural or social contexts, geography, and political events that may fluctuate over time (2).
As complex as this issue is, though, it is crucial that laboratory and other healthcare professionals confront it head-on and gain a full understanding of the ways in which race and medicine intersect—from the historical theories that have shaped modern medical misconceptions about race to its present-day use in healthcare. This understanding is essential to guiding efforts to end racial health disparities and make equitable healthcare for racial minorities a reality.
HOW GENETICS IS CHALLENGING RACIAL CATEGORIES
The astronomer Carl Sagan once said that “you have to know the past to understand the present,” and that is certainly true when examining the role of race in medicine. To understand the debate over the use of race in certain medical practices, you first have to understand that the idea of race as we know it today grew from a social framework that was intended to justify slavery.
While the concept of inherent physical and intellectual inferiority of non-European populations predates the pre-Civil War period in the United States by centuries, the modern concept of race took root in the 17th-18th centuries. With the rise of colonialism, the transatlantic slave trade began as a way to secure a cheap, controllable labor force to farm tobacco. At the time, assertions about innate social and physiological inferiority of non-European populations were promulgated to provide justification for the subjugation of African slaves.
Later, enlightenment period scientists promoted pseudoscientific theories that mirrored popular beliefs about the innate inferiority of non-European races. For example, the father of zoological taxonomy, Carl Linnaeus, categorized human beings into varieties or species based on continent of origin: Europaeus albus—White, Americanus rubescens—Red (Native American), Asiaticus fuscus—Sallow (Asian), and Africanus niger—Black. Linnaeus ascribed largely negative attributes to non-European “species” and particularly to individuals of African descent (3). Racism’s infiltration into science paved the way for innumerable atrocities against African American and Native American populations in the name of scientific and medical progress (4).
The influence of these pseudoscientific theories on the scientific and medical community—and the idea that races are biologically distinct—can still be seen in the argument that racial and ethnic categories can serve as a proxy for population genetics. However, genomic studies have revealed that the association between race and genetics is far more complicated.
Fast forward to 2001, when just over 90% of the human genome was mapped, enabling scientists to reexamine the relationship between race and genetics. Genetic analyses revealed that human DNA varies by approximately 1 in every 1,000 base pairs among individuals. Humans can be clustered based on geographic origin or ancestry, and although these groups correlate with traditional concepts of race, there are no sharp boundaries between ancestral populations. Rather, genetic variation is distributed in a continuous manner between ancestral groups. Even within ancestral clusters, there is more genetic heterogeneity between individuals within a given continental ancestry than between individuals with different continental ancestries.
In particular, ancestral African populations are the most genetically diverse (5). In the context of North America, historic admixture of Native Americans, Europeans, and largely enslaved Africans—combined with ongoing admixture from more recently immigrated populations—has resulted in highly mixed genetic ancestry (6).
THE USE OF RACE IN KIDNEY DISEASE DIAGNOSIS
Due to the inadequacy of race in delineating distinct, homogenous genetic ancestral populations, there is no gold standard for assigning an individual’s race in medical practice. Instead, race is often self- or socially ascribed based on surrogates such as skin color. This practice can introduce disparities in care.
In the wake of the racial reckoning that accelerated in 2020, many healthcare centers and institutions of higher learning embarked on diversity, equity, and inclusion activities, training, and educational programs. While many had advocated for the removal of race as a biological classifier for years prior, the use of race in medical algorithms came into sharp focus (1). Of particular notoriety was the use of race in estimating kidney function.
Kidney function is estimated by measuring the concentration of a substance in the blood known as creatinine. For the past 2 decades, the most widely used equations to estimate kidney function adjusted blood creatinine with correction factors to account for variability in creatinine between different sexes and age groups. These equations also assigned a correction factor that conferred an estimated kidney function for Black individuals that was 16%−21% higher compared to non-Black individuals of the same sex, age, and blood creatinine concentration, based on observations of higher creatinine in Black individuals.
However, multiple studies conducted in Black populations outside of the U.S. have demonstrated limited evidence for the use of a Black race correction in estimating kidney function (7). In 2020, a joint task force of the National Kidney Foundation and the American Society of Nephrology was therefore formed to reassess this practice. In 2021, after extensive deliberation and research, the task force, acknowledging that race is not a biological construct, recommended that labs immediately transition to race-agnostic estimates of kidney function (8).
While this change is likely to affect only a small subset of patients with kidney disease, it represents progress towards racial equity in diagnosing and treating this condition, particularly since Black and Hispanic individuals are at a higher risk of kidney failure, are less likely to receive patient-centric kidney replacement therapies, and are less likely to receive a kidney transplant compared to White individuals. However, much work remains, since socioeconomic factors also contribute to kidney health disparities in Black and Hispanic populations.
In an upcoming CLN issue, we will extend our discussion to examine why the inclusion of race in maternal serum screening also is not clinically warranted. As part of this discussion, we will review a national regulatory requirement (issued by the College of American Pathologists) that states that clinical laboratories performing maternal serum screening must calculate separate biomarkers for Black women when performing this screening.
RACE AND ETHNICITY AS REFLECTIONS OF SOCIAL DETERMINANTS OF HEALTH
Race might not be a reliable stand-in for physiology, but it can be used to guide patient care by shedding light on socioeconomic factors that affect health. This idea was documented in the book, “The Philadelphia Negro,” published in 1899 by African American sociologist W.E.B. Du Bois. In this seminal study on racial health disparities, Du Bois acknowledged that racial disparities in health were multifactorial but asserted that they were primarily attributable to socioeconomic differences between Black and White individuals. Du Bois’ publication was one of the earliest publications to reject the longstanding medical paradigm that attributed racial differences in health to innate biological attributes that differed between racial groups (9).
Du Bois’ insight on the impact of systemic socioeconomic inequities on racial health disparities has been refined and further developed over time. The socioeconomic factors that influence health are now described as social determinants of health. According to the U.S. Department of Health and Human Services, these are “the conditions in the environments where people are born, live, learn, work, play, worship, and age that affect a wide range of health, functioning, and quality-of-life outcomes and risks” (10). Social determinants of health further confound the use of race and ethnicity as proxies for genetic ancestry in medicine, since most diseases result from a complex interplay between genes and the environment.
Racial and ethnic minorities experience a disproportionate burden of negative social determinants of health, such as unemployment, poverty, and food insecurity. For example, in 2020, compared with the national average, Black, non-Hispanic households were twice as likely to be food insecure, and Hispanic households were 1.6 times more likely to be food insecure (10). Food-insecure adults are at an increased risk for obesity and chronic diseases, such as diabetes and hypertension, which are more prevalent in Black and Hispanic individuals and are leading risk factors for developing secondary health conditions such as kidney disease.
A UNIFYING TRUTH
The use of race in medicine is nuanced and complex. One unifying truth is that it is impossible to determine with certainty the precise sequence of DNA that is present in an individual based on visual inspection, so the practice of grouping persons into biologically distinct categories based on race and/or ethnicity is unscientific at best.
Racial and ethnic groups are both genetically and socioeconomically heterogeneous. In light of this, efforts to improve healthcare equity ideally should center the individual. Armed with an improved understanding of social determinants of health, and the knowledge that racial and ethnic minorities continue to experience a disproportionate burden of negative social determinants of health, we should be mindful of how our clinical practices may disadvantage these populations.
Christina C. Pierre, PhD, DABCC, FADLM, is a clinical assistant professor in the department of pathology and laboratory medicine at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia and a clinical chemist and section director of clinical chemistry and coagulation testing at Penn Medicine Lancaster General Hospital in Lancaster, Pennsylvania. +Email: [email protected]
- Vyas DA, Eisenstein LG, Jones DS. Hidden in plain sight—Reconsidering the use of race correction in clinical algorithms. N Engl J Med 2020; doi: 10.1056/NEJMms2004740.
- Olufadeji A, Dubosh NM, Landry A. Guidelines on the use of race as patient identifiers in clinical presentations. J Natl Med Assoc 2021; doi: 10.1016/j.jnma.2021.02.005.
- Byrd WM, Clayton LA. Race, medicine, and health care in the United States: A historical survey. J Natl Med Assoc 2001;93:11-34S.
- Washington HA. Medical apartheid: The dark history of medical experimentation on Black Americans from colonial times to the present. Anchor 2008.
- Jorde LB, Wooding SP. Genetic variation, classification and “race.” Nat Genet 2004; doi: 10.1038/ng1435.
- Micheletti SJ, Bryc K, Ancona Esselmann SG, et al. Genetic consequences of the transatlantic slave trade in the Americas. Am J Hum Genet 2020; doi: 10.1016/j.ajhg.2020.06.012.
- Marzinke MA, Greene DN, Bossuyt PM, et al. Limited evidence for use of a Black race modifier in eGFR calculations: A systematic review. Clin Chem 2021; doi: 10.1093/clinchem/hvab279.
- Delgado C, Baweja M, Crews DC, et al. A unifying approach for GFR estimation: Recommendations of the NKF-ASN Task Force on reassessing the inclusion of race in diagnosing kidney disease. Am J Kidney Dis 2022; doi: 10.1053/j.ajkd.2021.08.003.
- Williams DR, Sternthal M. Understanding racial-ethnic disparities in health: Sociological contributions. J Health Soc Behav 2010; doi: 10.1177/0022146510383838.
- U.S. Department of Health and Human Services, Office of Disease Prevention and Health Promotion, Healthy People 2030. Social determinants of health. https://health.gov/healthypeople/priority-areas/social-determinants-health (Accessed December 2022).
This article is the first in a special collection on health equity, diversity, and inclusion in laboratory medicine. Guest Editor Dina Greene, PhD, DABCC, FADLM, LetsGetChecked and University of Washington, Seattle