Kidney experts are pushing to remove race from medical algorithms.
Kidney experts push to remove race from medical algorithms
ALPHONSO HARRIED recently came across a newspaper clipping about his grandfather receiving his 1,000th dialysis treatment. His grandfather later died — at a dialysis center — as did his uncle, both from kidney disease.
“And that comes in my mind, on my weak days: ‘Are you going to pass away just like they did?’ ” said Harried, 46, who also has the disease.
He doesn’t like to dwell on it. He has gigs to play as a musician, a ministry to run with his wife, and kids to protect as a school security guard.
Yet he must juggle all that around three trips each week to a dialysis center in Alton, Illinois, about 20 miles from his home in St. Louis, to clean his blood of the impurities his kidneys can no longer flush out. He’s waiting for a transplant, just as his uncle did before him.
“It’s just frustrating,” Harried said. “I’m stuck in the same pattern.”
Thousands of other Americans with failing kidneys are also stuck, going to dialysis as they await new kidneys that may never come. That’s especially true of Black patients, like Harried, who are about four times as likely to have kidney failure as white Americans, and who make up more than 35 percent of people on dialysis but just 13 percent of the U.S. population. They’re also less likely to get on the waitlist for a kidney transplant, and less likely to receive a transplant once on the list.
An algorithm doctors use may help perpetuate such disparities. It relies on race as a factor in evaluating all stages of kidney disease care: diagnosis, dialysis and transplantation.
‘Disparities and inequities’
It’s a simple metric that uses a blood test, plus the patient’s age and gender and whether they’re Black. It makes Black patients appear to have healthier kidneys than non-black patients, even when their blood measurements are identical.
“It is as close to stereotyping a particular group of people as it can be,” said Dr. Rajnish Mehrotra, a nephrologist with the University of Washington School of Medicine.
This race coefficient has recently come under fire for being imprecise, leading to potentially worse outcomes for Black patients and less chance of receiving a new kidney. A national task force of kidney experts and patients is studying how to replace it. Some institutions have stopped using it.
But how best to assess a patient’s kidney function remains uncertain, and some medical experts say fixing this equation is only one step in creating more equitable care, a process complicated by factors far deeper than a math problem.
‘A point of no return’
Kidneys filter about 40 gallons of blood a day, like a Brita filter for the body. They keep in the good stuff and send out the bad through urine. But unlike other organs, kidneys don’t easily repair themselves.
“There’s a point of no return,” said Dr. Cynthia Delgado, a University of California-san Francisco nephrologist who is leading the task force working on the national recommendation to ditch the racial part of the equation.
Furthermore, it’s hard to gauge whether kidneys are working properly. Gold-standard tests involve a chemical infusion and hours of collecting blood and urine to see how quickly the kidneys flush the chemical out. An algorithm is much more efficient.
Buoyed by activism around structural racism, those seeking equity in health care have recently been calling out the algorithm as an example of the racism baked into American medicine. Researchers writing in the New England Journal of Medicine last year included kidney equations in a list of race-adjusted algorithms used to evaluate parts of the body — from heart and lungs to bones and breasts. Such equations, they wrote, can “perpetuate or even amplify race-based health inequities.”
In March, ahead of the national task force’s upcoming formal recommendation, leaders in kidney care said race modifiers should be removed. And Fresenius Medical Care, one of the two largest U.S. dialysis companies, said the race component is “problematic.”
Part of the equation
Until the late 1990s, doctors primarily used the Cockcroft-gault equation. It didn’t ask for race but used age, weight and the blood level of creatinine — a chemical that’s basically the waste left after muscles move. A high level of creatinine in the blood signals that kidneys are not doing their job of disposing of it. But the equation was based on a study of just 249 white men.
Then researchers wrapping up a study on how to slow down kidney disease realized they were sitting on a mother lode of data that could rewrite that equation: gold-standard kidney function measurements from about 1,600 patients, 12 percent of whom were Black. They evaluated 16 variables, including age, sex, diabetes diagnosis and blood pressure.
They landed on something that accurately predicted the kidney function of patients better than the old equation. Except it made the kidneys of Black participants appear to be sicker than the gold-standard test showed they were.
The authors reasoned it might be caused by muscle mass. Participants with more muscle mass were likely to have more creatinine in their blood, not because their kidneys were failing to remove it, but because they just had more muscles producing more waste. So they “corrected” Black patients’ results for that difference.
‘Fiddling with the algorithms’
Dr. Andrew S. Levey, a professor at Tufts University School of Medicine who led the study, said it doesn’t make intuitive sense to include race — now widely considered a social construct — in an equation about biology.
Still, in 1999, he and others published the race equation, then updated it a decade later. Though other equations exist that don’t involve race, Levey’s latest version, often referred to as the “CKD-EPI” equation, is recommended for clinical use. It shows a Black patient’s kidneys functioning 16 percent better than those of a non-black patient with the same bloodwork.
It might not be that Black bodies are more likely to have more creatinine in the blood, but that Americans who experience housing insecurity and barriers to healthy food, quality medical care and timely referrals are more likely to have creatinine in their blood — and that many of them happen to be Black.
Delgado and Levey agree that removing race from the formula might feel better on the surface, but it isn’t clear the move would actually help people.
“Fiddling with the algorithms is an imperfect way to achieve equity,” Levey said.