The first sign that something was wrong with Curtis Warfield came in 2005, when a laboratory test found protein in his urine during a routine checkup. In 2012, Warfield was diagnosed with stage 3 kidney disease. Two years later he started dialysis.
“When you get diagnosed, you sit there like a deer in the headlights. You don’t know what’s going on. You don’t know what’s going to happen,” Warfield said. “All you know is that you have this disease.”
Warfield, a black man, was 52 years old, was healthy and had no family history of kidney disease. As his condition worsened and he worked his way through treatment options, he unknowingly experienced a form of racism: a mathematical equation that counted his race when estimating his kidney function.
That equation, called the estimated glomerular filtration rate or eGFR, is a key variable that helps determine the course of treatment for an estimated 37 million people with kidney disease across the country. The eGFR equation estimates how well a person’s kidneys filter blood, taking into account a person’s age, gender and levels of creatinine, a waste product naturally produced by people’s bodies and removed through the kidneys. But there has long been a controversial variable: race.
If a person identifies as black, the score is adjusted and increased. No other breeds are included in the comparison. As a result, black people have higher eGFR scores than people of other races. These scores, which estimate how well the kidneys are functioning, influence doctors’ treatment recommendations. The lower the score, the greater the chance that a patient will start dialysis or even receive a kidney transplant.
As the disparities faced by Black people with kidney disease became more widely studied, race-based eGFR was increasingly challenged by nephrologists, high-profile kidney disease organizations and, crucially, medical students who questioned their educators about the biological basis for creating distinction between Black and non-Black people.
Warfield has been advocating for other people with kidney disease since he received a transplant in 2015. In 2020, he joined a multi-organization task force led by the National Kidney Foundation. The task force has spent months delving into the issue and challenging the inclusion of racial discrimination. in the eGFR, and ultimately initiated two new equations for estimating renal function.
The new, race-neutral equations came out last fall. And in February, the United Network for Organ Sharing (UNOS), the nonprofit organization that manages the organ donation and transplant system in the US, proposed dropping the use of the racial eGFR in favor of a race-neutral eGFR. As a result, kidney care in the US is at an inflection point in which it is moving away from a deeply ingrained, institutionally racist equation.
Removing the race factor from kidney estimates is a crucial step in reducing disparities in kidney diseases and treatments, according to specialists on the National Kidney Foundation task force. Black Americans are disproportionately at risk for conditions that contribute to kidney disease, such as high blood pressure, diabetes and heart disease. Although Black people make up less than 14% of the population in the US, this includes 35% of people on dialysis, according to the National Kidney Foundation.
“People who are black are much less likely to be referred for a transplant, even if they are on dialysis. When they are referred, they are much less likely to be mentioned. If they are mentioned, they are much less likely to receive a kidney transplant. There are differences at every step,” says Rajnish Mehrotra, MD, chief of nephrology at Harborview Medical Center and professor of nephrology and medicine at the University of Washington.
These differences were the basis for increased questions from medical students in recent years, Mehrotra said, especially when it came to the equation the students learned to assess kidney function.
“They were told in class that there is an equation that reports a different number if you are black than if you are not black. And they challenged the premise of that, like, ‘What’s the evidence that there’s a difference there?'” Mehrotra said. “And so the deeper we dug in terms of looking for evidence to support differential reporting by race, we found that the evidence supporting this is not strong at all.”
University of Washington Medicine, where Mehrotra works, became one of the first institutions to eliminate the race variable from the eGFR equation in June 2020.
But a broader movement was also underway, involving the major professional associations for kidney specialists, the National Kidney Foundation and the American Society of Nephrology, as well as patient advocates (including Warfield), physicians, scientists, and laboratory technicians. meet with the goal of phasing out the racial eGFR in favor of a race-neutral approach.
In June 2021, a year after Washington Medicine dropped the racial eGFR, the task force formed by these organizations released an interim report questioning the use of race as a factor in diagnosing kidney care.
According to the report, the race variable in the eGFR was created based on research from the 1990s. The Modification of Diet in Renal Disease (MDRD) study, published in 1999, was one of the first to include black people – an earlier equation for estimating kidney function was based entirely on information from white, male patients – and there higher levels of serum creatinine were found. among black adults than among their white counterparts, the task force authors write in their report.
At the time of the MDRD, making a mathematical adjustment based on race was seen as progress because including black people in studies at all was progress, the report said.
But within the MDRD, there is a troubling justification for higher creatinine levels among black people: previous studies had shown that “black people, on average, have greater muscle mass than white people.” The three studies cited there, published in 1977, 1978 and 1990, compared several health measures, including serum creatinine kinase and whole-body potassium levels, in black and white study participants. The studies all argue that separate reference standards are needed for black people, attributing differences in results to differences in racial biology.
Today these conclusions would be disputed.
“Our understanding of race has evolved over the past quarter century,” said Paul Palevsky, MD, chairman of the National Kidney Foundation and professor at the University of Pittsburgh, one of the lead organizations on the task force. “Race is not biologically based, but is much more of a social construct than anything else.”
In September 2021, the task force released two new equations that estimate kidney function. Neither uses race as a factor. One is very similar to the racial eGFR, which measures creatinine. The other equation adds a second test that measures cystatin C, another chemical in the blood that serves as a filtration marker.
Both comparisons are recommended because while creatinine testing is available in virtually all labs nationwide, cystatin C is not, leading to a higher price tag and reduced access to the test. The process of moving laboratory practices toward the new standard is underway, Palevsky said, and he is hopeful that major labs will implement the change in the coming months.
“In medicine, the time it normally takes from the time a guideline or recommendation for a clinical practice is published to the time it actually appears in clinical care is about ten years,” Palevsky said. “In this case, we see a very rapid implementation of the new equation.”
The new equations are slightly less accurate compared to the old equation, Palevsky and Mehrotra agree. But the estimates are just that – estimates – and should be used as just one part of a much more comprehensive clinical analysis of a person’s health and needs.
And because racial disparities in medicine continue to be studied and understood, the consequences of considering race in health care decisions can have a corrosive effect beyond an individual person and their diagnosis, Palevksy said. “As we teach medical students and physicians, we are reinforcing for them this concept, this false concept, that race is a biological determinant of disease, which is not the case,” Palevsky said.
Systemic racism affects Black people’s health outcomes in many different ways, from chronic stress from experiencing racism to limited access to healthy food to healthcare provider bias. These problems are deep-rooted and require their own sustainable solutions.
However, the new eGFR equation is a step in the right direction, Palevsky said.
“Will it solve the problem of inequity in kidney care? I think we are fooling ourselves if we think that a simple change in an equation will solve many, many deeper-rooted problems,” Palevski said. “Certainly, changing an equation will not solve the problems of inequality, many of which are rooted in historical racism.”
These disparities will only be meaningfully reduced through large-scale investments in the health of poor communities. But the eGFR comparison is nonetheless a meaningful step for Black people with kidney disease. The benefits of the new eGFR equation, Warfield said, extend beyond the equation itself.
“It opens eyes and doors to other inequities that are going on, at least within the kidney community, and gets people talking about it and looking at what’s going on,” Warfield said. “It’s good to know that the patient’s voice is now at the table and being listened to, and not just determined by the medical community.”