Editor’s Note: CNN’s “History Refocused” series features surprising and personal stories from America’s past to bring depth to conflicts still raging today.
When she first learned about race correction, Naomi Nkinsi was one of five Black medical students in her class at the University of Washington.
Nkinsi remembers the professor talking about an equation doctors use to measure kidney function. The professor said eGFR equations adjust for several variables, including the patient’s age, sex and race. When it comes to race, doctors have only two options: Black or “Other.”
Nkinsi was dumbfounded.
“It was really shocking to me,” says Nkinsi, now a third-year medical and masters of public health student, “to come into school and see that not only is there interpersonal racism between patients and physicians … there’s actually racism built into the very algorithms that we use.”
At the heart of a controversy brewing in America’s hospitals is a simple belief, medical students say: Math shouldn’t be racist.
The argument over race correction has raised questions about the scientific data doctors rely on to treat people of color. It’s attracted the attention of Congress and led to a big lawsuit against the NFL.
What happens next could affect how millions of Americans are treated.
Medicine has never been immune to racism
Carolyn Roberts, a historian of medicine and science at Yale University, says slavery and the American medical system were in a codependent relationship for much of the 19th century and well into the 20th.
“They relied on one another to thrive,” Roberts says.
It was common to test experimental treatments first on Black people so they could be given to White people once proven safe. But when the goal was justifying slavery, doctors published articles alleging substantive physical differences between White and Black bodies — like Dr. Samuel Cartwright’s claim in 1851 that Black people have weaker lungs, which is why grueling work in the fields was essential (his words) to their progress.

The effects of Cartwright’s falsehood, and others like it, linger today.
In 2016, researchers asked White medical students and residents about 15 alleged differences between Black and White bodies. Forty percent of first-year medical students and 25% of residents said they believed Black people have thicker skin, and 7% of all students and residents surveyed said Black people have less sensitive nerve endings. The doctors-in-training who believed these myths — and they are myths — were less likely to prescribe adequate pain medication to Black patients.
To fight this kind of bias, hospitals urge doctors to rely on objective measures of health. Scientific equations tell physicians everything from how well your kidneys are working to whether or not you should have a natural birth after a C-section. They predict your risk of dying during heart surgery, evaluate brain damage and measure your lung capacity.
But what if these equations are also racially biased?
Race correction is the use of a patient’s race in a scientific equation that can influence how they are treated. In other words, some diagnostic algorithms and risk predictor tools adjust or “correct” their results based on a person’s race.
The New England Journal of Medicine article “Hidden in Plain Sight” includes a partial list of 13 medical equations that use race correction. Take the Vaginal Birth After Cesarean calculator, for example. Doctors use this calculator to predict the likelihood of a successful vaginal delivery after a prior C-section. If you are Black or Hispanic, your score is adjusted to show a lower chance of success. That means your doctor is more likely to encourage another C-section, which could put you at risk for blood loss, infection and a longer recovery period.
Cartwright, the racist doctor from the 1800s, also developed his own version of a tool called the spirometer to measure lung capacity. Doctors still use spirometers today, and most include a race correction for Black patients to account for their supposedly shallower breaths.
Turns out, second-year medical student Carina Seah wryly told CNN, math is as racist as the people who make it.
Race isn’t based on biology
The biggest problem with using race in medicine? Race isn’t a biological category. It’s a social one.
“It’s based on this idea that human beings are naturally divided into these big groups called races,” says Dorothy Roberts, a professor of law and so