New Test Measures Kidney Health Without Factoring in Race
Scientists are developing new ways of evaluating kidney health that don’t make potentially harmful assumptions based on the patient’s race.
Quick, commonplace lab tests to screen for kidney problems produce a number, called eGFR, that then gets adjusted upwards by as much as 21 percent if the patient is Black. It’s based on decades-old research that many experts now call flawed, and it might make a doctor conclude that a Black patient’s kidneys are functioning better than they actually are.
But because race isn’t a biological category like sex or age, many kidney specialists say it shouldn’t be a part of this widely used blood test. Using it might cause harmful differences in the way patients are treated, potentially delaying Black patients’ access to specialty care or even slowing their pathway to being placed on a waitlist for a lifesaving kidney transplant.
A medical test described in a new research paper published in the American Journal of Kidney Diseases combines four different blood tests to arrive at a more accurate estimate of how effectively a person’s kidneys are filtering their blood, which is what doctors use to monitor a person’s kidney health.
By using four tests rather than one, the researchers say they’re able to stop relying on assumptions about a person’s body based on their race.
Lesley Inker, MD, director of the Kidney Function and Evaluation Center at Tufts Medical Center and the lead scientist behind the new research, also helped to develop earlier methods of estimating kidney function that do use race. Now she says it’s vital to come up with an accurate alternative to race-adjusted algorithms. It’s a goal propelled in part by mounting pressure from doctors, medical students, and even some members of Congress.
“The medical and scientific community should be responsive to these really important questions that are being asked, and we should spend time to understand them and answer them,” Inker tells Consumer Reports.
The method she and her co-authors propose won’t be available right away. One of the four tests it requires is not currently approved by the Food and Drug Administration.
Plus, the new testing method would be more expensive than the most common screening tests used today. For that reason, the new protocol would most likely be used as a follow-up to confirm results from less expensive, but also less accurate, kidney function tests, Inker says.
The new method is “just a step forward,” says Rajnish Mehrotra, MD, interim head of nephrology at the University of Washington in Seattle, who was not involved in the research. In part, that’s because it’s unlikely to be “cheap and widely available,” he says.
Broader Changes Coming
Developing new, more advanced tests is just one part of a broad effort to remove race from kidney-function estimates. This year, several major hospitals have simply dropped the race variable from the more common, cheaper first-line test that gives Black patients different scores from the ones non-Black patients receive.
Recently, hospitals affiliated with Dartmouth College joined other major institutions, including Massachusetts General Hospital and the University of Washington, in nixing race from the equation.
Scrapping the variable can have mixed effects. Researchers at Harvard Medical School recently found that dropping race from the existing equations helps increase Black patients’ access to important care, but it can also make it harder for some Black patients to get certain important medications. And an October study of Boston-area patients found that a substantial number of Black patients would be classified as having more severe kidney disease if their race were no longer considered in the kidney function equation.
Critics argue that more research is needed to ensure that it’s safe to drop race considerations from existing tests.
But Mehrotra says the benefits of stopping the use of race outweigh the drawbacks. His university dropped the race adjustments it had been using in June 2020 and, according to Mehrotra, that change has been a success.
A broader shift could come in the next month, when a task force convened by two leading kidney-related professional medical associations is due to come out with recommendations for making kidney function tests fairer. Suggestions made by the group—which includes Inker, at Tufts—are likely to be taken up by medical laboratories and physicians across the country, who look to professional associations to standardize the care they provide.
The push to rethink race-adjusted clinical algorithms has advanced the furthest in kidney medicine, but nephrologists aren’t the only ones working to remove race from equations used to make critical medical decisions.
In a recent letter to the House Ways and Means Committee, the president of the American Society of Nephrology wrote that his organization is in contact with several professional societies that are considering similar changes in other medical fields. Those specialties include cardiology, obstetrics, and pulmonology, according to an ASN spokesperson.
The proposed new kidney function test demonstrates that race-free clinical algorithms are within reach, says David Jones, MD, a Harvard Medical School professor and co-author of an influential June paper in the New England Journal of Medicine about race-adjusted algorithms in various medical fields. “This article suggests that when researchers set their minds to it, they can figure out alternatives that produce the desired clinical objectives without resorting to unscientific race categories,” Jones tells CR.