On May 29, UW Medicine in Seattle announced that it would no longer use patients' race to calculate how well their kidneys worked.
That race was a factor at all in kidney function may sound puzzling to an outsider, but in fact, race is used in a number of calculations across medical specialties when it comes to making clinical decisions, according to a paper published Wednesday in The New England Journal of Medicine.
Efforts to change the kidney function test at the Seattle institution were driven by University of Washington School of Medicine student Naomi Nkinsi.
"I saw repeated over and over again that race was a risk factor for disease. And the implication was that having black skin meant that you were inherently more susceptible to a disease," Nkinsi told NBC News.
"I decided to look at the kidneys just because it was one very concrete example where race is used in an algorithm," Nkinsi said.
The test, known as glomerular filtrate rate, or GFR, in essence tells doctors how well the kidneys are working to filter waste from the body. It's one of the calculations also highlighted in The New England Journal report.
GFR is calculated using equations that have a different standard if the patient is Black, stemming, in part, from the dated belief that Black people have more muscle mass, the paper's senior author, Dr. David Jones, a professor of the culture of medicine at Harvard Medical School, said. The thought, he continued, is that greater muscle mass leads to more breakdown products that must be filtered through the kidneys, so the equations are adjusted to account for that.
The result often leads to higher GFR values for Black patients, implying that their kidneys may be working better than they are. That could cover up potential health issues and affect how patients are referred to specialists or for kidney transplants, the paper said.
The question of taking race out of the GFR equation is something that has been discussed for a while, said Dr. Deidra Crews, the associate vice chair for diversity and inclusion in the department of medicine at Johns Hopkins Medicine in Baltimore. She was not involved with the New England Journal paper.
Crews, who is also a kidney specialist, said the topic has come up more and more in recent years.
In addition to UW Medicine, other institutions, including Beth Israel Deaconess Medical Center in Boston and Zuckerberg San Francisco General Hospital, have also stopped using the race-based formula.
The New England Journal paper described other instances across medical specialties in which race is factored into decision-making, including when considering heart surgery or even C-sections.
The paper also explored the consequences of these biases.
"If you look at almost all of the race calculators that are out there, the net effect of them is to direct more medical resources towards white people than Black people. I don't think that's anyone's intent, but that's what happens," Jones said.
Jones, a psychiatrist, said equations encompassing race aren't used in his field. But his students had recently been asking why such equations are used.
Crews said the paper "raises some really important things that need to be considered in medicine in general."
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Still, some doctors remain in favor of a race-based equation for kidney function. According to a study published in March in JAMA Internal Medicine, eliminating race from the GFR equation could lead to inappropriately early kidney transplants or dialysis, overdiagnosis of chronic kidney disease and inadequate dosing of drugs.
Jones said he doesn't think race should be eliminated from medicine. Rather, he wants it to be looked at in a different way.
"I think race is an essential part of the descriptive statistics that doctors do. We really need to know that COVID mortality rates are higher in Blacks and Hispanics than in whites," he said. "Where I become uncomfortable is when you turn that descriptive statistic into a prescriptive tool, like these race calculators or these race adjustments to diagnostic tests."
Crews expressed concern about how race is sometimes used in medical decision-making.
"It's sort of gotten to the point where, for a lot of clinicians, I'm afraid they view race as a proxy of biology," she said. "And that's just not what it is."