How race became ubiquitous in medical decision-making tools

It was created with the best intentions: a government policy asking researchers to collect racial data to help address health disparities. But it may have had an unintended opposite effect, paving the way for the problematic use of race in an array of medical decision-making tools.

Starting in the 1990s, the National Institutes of Health began requiring the collection and reporting of racial data in its funded research. It was a major pivot point, revealing in stark, undeniable numbers racial divides in health outcomes. But to a new generation of researchers, that quantification enabled the development of algorithms that misused race as a health risk factor.

Poorly understood correlations between race and outcomes were embraced as a way to make disease-risk calculations more precise, though the race data were actually quite imprecise. 

It was a time when many in medicine, new to handling race data, used it in a sloppier way than they would today. Many categorized research subjects as simply being Black, Hispanic, or Asian without thinking about the complex ancestry within those groups. 

Many also still considered race a biological explanation for differences, and not, as scientists agree today, a socially created category — with a weak relationship to genetic differences — that may be more connected to characteristics like income or neighborhood. In some instances, researchers devising new algorithms uncritically accepted faulty ideas about racial differences that date back to America’s slavery era.

“All we have is old research that was accepted under a lower standard of rigor,” said Lou Hart, medical director of health equity at Yale New Haven Health System. The federal government said, “‘You have to diversify your clinical trials. You have to report out this type of information and publish literature.’ And so people did.”

Eliseo Pérez-Stable, director of the National Institute on Minority Health and Health Disparities, said the collection of racial data “categorically” did not lead to the creation of race-based algorithms. “The reason we collect race and ethnicity, and we should collect other things like socioeconomic status that we don’t, is because they influence health outcomes in ways that we don’t fully understand,” he said. 

Along the path to better understanding, racial data were collected inconsistently: Sometimes participants were asked, sometimes study leaders just guessed. And researchers often divided the world simply into Black and white, ignoring those who were other races or mixed race. 

“The suggestion that Black people and only Black people are different than every other human on the planet is just ludicrous,” said Vanessa Grubbs, a nephrologist in Oakland, Calif. and a leading voice calling for the removal of race from algorithms used to assess kidney function.

Kidney function is estimated using a blood test that measures levels of creatinine, a waste product created when muscle breaks down that is filtered out by healthy kidneys. Studies found that, on average, Black people have higher levels of creatinine, leading researchers to introduce a race adjustment for Black people into the kidney algorithm.  

In their original paper published in 1999, creators of the algorithm attributed high creatinine levels to Black people being more muscular — an assertion that was not widely questioned at the time but has more recently come under scrutiny for overgeneralization and racial stereotyping. The algorithm was updated with a more diverse subject pool, but the concept that Black muscle mass was a reason for difference persisted. 

The idea that Black patients would have greater muscle mass was easy to believe, perhaps, because of the United States’ history of slavery. As recently as 2011, one urologist hypothesized that enslaved Africans who survived the passage to the Americas would have had greater lean muscle mass; others pointed out that those who were enslaved were “bred” for greater strength. 

“When you ask where did these algorithms come from, not all roads, but many roads lead back to slavery-era race science,” said David Shumway Jones, a historian of science, physician, and professor at Harvard Medical School. “The notion that Black people have different skin, different bones, different bone density, it all goes back to these pre-Civil war claims.” 

Until recently, even some high-profile scientific papers used race in ways that would not pass muster today. The studies cited in the kidney algorithm paper to suggest that higher creatinine levels in Black people were due to muscle mass were extremely thin; some were decades old. 

None of the three cited studies — all small and using subjects from a single town, hospital, or in one case, staff at a single lab and their friends — directly measured muscle mass. One looked at body fat in children, another at potassium levels. 

Health equity advocates don’t believe the equation creators were out to harm Black people. “No one was meeting in back rooms or alleys saying, ‘How can I hurt Black patients?’’’ said La’Tonzia Adams, a pathologist in Portland, Ore., working with the College of American Pathologists to ensure new race-free algorithms are being implemented. “This started with good intent.” 

Instead, they say the mostly white people leading the field of nephrology and at its journals never questioned the careless thinking because notions that races differ biologically were so accepted. “These ubiquitous and pervasive race claims have been in medicine forever,” said Jones, who has examined how the New England Journal of Medicine has historically handled issues of race. “It’s very easy for editors not to notice them.” 

Oversimplistic thinking about race has been repeated across medical specialties. For decades, hypertension in Black Americans was explained away because of the “salt-slavery hypothesis,” which posited that high blood pressure could be due to salt deficiencies in regions of Africa where enslaved people were stolen from, the trauma of the slave trade, or conditions of slavery. That idea was easily debunked by historians who showed that there wasn’t a salt deficiency at the time and that hypertension rates are not high among present-day West Africans.

There’s a similar issue with the race-adjusted STONE score algorithm developed to diagnose kidney stones. The presence of flank pain is considered as important as finding blood in urine — unless you’re Black. This algorithm stems from a single study conducted in 2014 at two hospitals in Connecticut finding that Black people were less likely to have kidney stones — data points now deeply questioned by those in the field, and being reevaluated by Hart and his colleagues. 

In obstetrics, the unfounded slavery-era notion that the pelvises of Black women were narrow, “degraded and animalized,” remained a “concerning echo” in a birth risk calculator — causing some U.S. doctors to discourage vaginal deliveries after a C-section for Black women. In Canada, the mother’s race isn’t a factor. “Are pelvises different in Canada?” Jones asked. 

In pulmonology, a sweeping generalization that Black people have lower normal lung function led physicians to long overlook chronic lung disease in Black patients. The idea, as chronicled by the late Lundy Braun, who was a professor of Africana Studies and pathology at Brown University in her history of the spirometer, traces to 1851. 

Physician Samuel Cartwright built his own spirometer to measure lung function, which he quantified at 20% lower in Black people he enslaved. Cartwright argued that Black people needed to be forced to work or their weak lungs would suffer. “You can imagine what a powerful justification this is for enslaving human beings,” said Dorothy Roberts, a professor of law and sociology at the University of Pennsylvania.

For centuries, this racist concept echoed in clinicians’ estimates of lung function and adjustments of up to 15% to spirometer readings, which indicated the lung disease of Black people was less severe than the devices indicated. In March 2023, the American Thoracic Society urged that race and ethnicity should no longer be used to interpret spirometry results. 

“Essentially structural racism is baked into the numbers because of what we set the norm at,” said Lauren Kearney, a pulmonology fellow who helped usher in race-free spirometry assessments at Boston Medical Center. “In the past, we were told in medical school that race does define biology.” 

A number of new studies estimate the lung test adjustment has taken a toll. It has prevented or delayed disability and workers’ compensation payments for Black workers, and has led to missed cases of respiratory disease and severe lung impairment, more uncontrolled asthma, and the underestimation of COPD severity in Black patients. 

Not all racial misconceptions have manifested in algorithms; some simply bled into medical practices that put Black patients at higher risk. For decades, radiologists, dentists, and manufacturers of X-ray equipment internalized the idea that Black people have thicker skin and denser bones, and therefore irradiated them with higher doses, until the practice was stopped in the 1970s. 

There’s no direct evidence the practice increased cancer risk. But it highlights the easy adoption of racial categories in medicine, said Itai Bavli, a postdoctoral fellow in applied ethics at the University of British Columbia and lead author of a paper about the topic published in NEJM in 2022. The paper chronicled numerous characterizations in medical literature of Black skin as “perfectly opaque;” Black flesh as “harder;” and Black bones and skulls as “thicker and denser” or “almost impregnable.” 

“The belief that Black people are different was so widespread,” said Bavli. “One might have expected X-ray technologies, which see through the skin to deeper structures beneath, to be spared racialization. They were not.” 

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