Expert panel recommends against use of race in assessment of kidney function

An expert task force on Thursday released a new and much-anticipated approach for diagnosing kidney function, saying there is no need for controversial algorithms that consider race in the assessment of kidney disease.

The new recommendations come as a victory for a growing number of physicians and activists who argue the use of race-based tools in medicine is outdated and wrong because race is not a good proxy for genetic difference — and sends the message that some races are biologically inferior. Many also argue that the separate racial thresholds for classifying kidney disease underestimate the extent of disease in Black patients, leaving them less likely to receive the speciality kidney care they need or be placed on transplant waitlists.

Black Americans are four times more likely than white Americans to have kidney failure and, despite having higher rates of end-stage kidney disease, are less likely to receive kidney transplants.

advertisement

Using equations, or algorithms, to refine lab results is a long-standing practice in medicine. The first commonly used equations for assessing kidney function came into place in the mid-1970s, and may have been faulty from the start because they were based on a patient sample that included only white men. Those equations were first adjusted for sex. Then, in the late 1990s, when studies showed Black patients had higher average levels of creatinine — a byproduct of muscle metabolism that is a marker for kidney function — than white patients, the equations were adjusted for race, in an effort to provide more accurate estimates.

But using race as a proxy for genetics is problematic since studies show race is not always reported accurately or inclusive of people who are multiracial. Some of those early studies on creatinine levels were likely imprecise, with one determining race “probably by examination of skin color.” Ancestry can be far more important than race in determining genetic susceptibility to disease, but is rarely tested for in most clinic settings. Many also argue there is no biologically plausible reason to explain why some Black patients may have higher serum creatinine levels and that levels of the marker can vary more between people from the same race than in people from different races.

advertisement

The task force report recommends the use of a revised equation with no racial correction to estimate kidney function (or GFR, glomerular filtration rate) using serum creatinine. The equation is called “the eGFR 2021 CKD EPI creatinine equation” and is considered a “refit” equation because it doesn’t simply drop the racial correction from the previously used equation, but was recalculated using data from a large and diverse pool of patients. The new equation is one of 26 approaches considered by the task force.

Because creatinine tests are useful for screening but may need further confirmation, the report makes a second recommendation. It encourages clinicians who need more information about kidney function to order tests for a different blood marker — cystatin C — which, when used with creatinine, provides a better indicator of kidney function than either test alone. (Cystatin C has not been used routinely as a marker because tests for it are not available in most labs or on high volume analyzers and it is also more expensive; task force members hope these things will change in the near future as demand for the better test grows.)

“If I had my way, I’d want everyone to go out and have the option to use these [combination] tests tomorrow, but this isn’t yet in every lab,” said Lesley A. Inker, a task force member and director of the Kidney Function and Evaluation Center at Tufts Medical Center who led the CKD-EPI research team that developed the new equations. For now, she said, the new equations that do not include race provide highly accurate results and can be used immediately.

The task force report was issued on the same day as two new reports in the New England Journal of Medicine, one that showed that cystatin C works better as a diagnostic tool, and one that described the new recommended equations and showed, while not perfect, they were far more accurate in Black patients and off by only minor amounts in non-Black patients. An editorial in the journal said shedding the race correction was an important step that could lead to earlier identification and care of patients most at risk.

Complaints over the use of racial algorithms have been bubbling for years but grew increasingly loud last year as a widespread racial reckoning spread across the country. Due to concerns raised by medical students and trainees, some large hospital systems, including at Vanderbilt University and the University of Washington, have already dropped the racial correction, while others were awaiting the task force report for guidance.

Some nephrologists had argued that dropping the race correction could lead to other inequities for Black patients, such as improper dosing for some medicines and chemotherapy, not being eligible for life insurance due to being diagnosed with kidney disease, or not being able to become kidney donors.

Saying they did not want to cause additional harm with new recommendations, the 14-member task force of the National Kidney Foundation and American Society of Nephrology waded through these issues deliberatively, considering hundreds of papers, hours of expert testimony, and input from patients. The panel unanimously agreed that the use of race in assessments was not appropriate. “I’m glad we could uphold medical quality with utmost scientific rigor while embracing social change,” said Cynthia Delgado, an associate professor at the University of California, San Francisco, and associate chief of nephrology at the San Francisco VA Medical Center who was a co-chair of the task force. “Patients can be reassured there is equity in how they are being assessed.”

While task force leaders said they could not discuss their internal deliberations, some said the debate was contentious at times and that it took the group longer than expected — an entire year — to reach consensus. Some had worried the task force might take years to arrive at a decision, or postpone a decision by issuing a call for more data.

NKF President Paul Palevsky, a nephrologist, hailed the decision as a major improvement that will be a step toward health equity in his field, but said much more needed to be done. “Including race in equations for GFR, or any other algorithms in medicine, delivers the wrong message. It reinforces this concept that skin color drives biology, which is not the case,” he said. “But anyone who thinks this is the whole solution, that we’re done addressing race and racism in the treatment of kidney disease is deluding themselves.”

Vanessa Grubbs, a San Francisco Bay Area nephrologist who has been fighting against the algorithms for more than a decade, said “the fact that it took a national task force to do this shows how entrenched systemic racism is in medicine.”

“It’s great they did this, but the fact that it took years, and I don’t know how many meetings deliberating what we already knew, shows how obsessed this country is with trying to prove the races are inherently different,” Grubbs said.

Palevsky said the recommendation to use a “refit” creatinine equation without a racial correction would require no changes or upgrades to laboratory equipment, just changes to software and possibly the codes used to facilitate the exchange or pooling of lab results. His foundation has been prepping and educating leaders of labs that process medical tests. “They have been very engaged,” he said. “They are primed for this.”

He said patients could check kidney function under the revised equation using a calculator on the NKF website. Many Black patients whose kidney function may have been underestimated using the racial correction may find themselves moved into an advanced stage of disease, or even to the point where they would be recommended for a transplant. He advised patients to discuss any concerns with their physician or a nephrologist.

Mallika L. Mendu is a nephrologist who served on the task force and executive medical director of clinical operations for Brigham Health, which abandoned the race correction for kidney diagnostics in June 2020 after protests by medical students and residents. Wondering how removal of the racial correction would affect patients, she helped conduct a study to see how some 2,000 Black kidney patients in the Mass General Brigham health care system would be reclassified.

Mendu found that removing the race multiplier led to 1 in 3 patients being reclassified with more severe kidney disease, with many moving into stage 4, the final stage before kidney failure. She also found 64 patients who had not previously been eligible meeting criteria for kidney transplants. Her findings, she said, supported removing the race-based algorithms that she had not previously questioned.

“Honestly, I took this as gospel, I didn’t even think about it. It shows you our generation didn’t always question what we were taught,” said Mendu, who graduated from medical school in 2009. “It makes me really proud of this generation of medical students who are questioning everything.”

Mendu said the medical student protests, which started in her hospital around 2016, made her reexamine the algorithms she’d long taken for granted as correct. “A lot of people said, ‘This is based on good science. Don’t open this can of worms.’ But when I looked at it, it didn’t make sense to me,” she said.

While she’s happy with the new recommendations, Mendu said she, like other task force members, thinks the work needed to end health disparities in her field is only beginning. Her study showed that even when Black patients qualified for transplant under the racially corrected algorithm, they were still rarely referred for transplant. “My hope,” she said, “is that this is the start of conversation to end these truly profound disparities.” 

Source: STAT