On October 1, 2020, the University of Wisconsin School of Medicine and Public Health (UWSMPH) and UW Health removed race from a formula routinely used to assess kidney function.
With conversations about racism and equity circulating the country, Marin Darsie, MD, assistant professor, Emergency Medicine and Neurosurgery, was thinking about inequities in medicine. That is when she posed a question to Arjang Djamali, MD, MS, professor, Nephrology, that few have asked in the past 20 years: is the standard formula for estimating kidney function racist?
To test kidney function, doctors use a creatinine-based glomerular filtration rate estimation formula (GFR). When this formula was established 20 years ago, studies showed that Black people had higher GFRs for the same creatinine levels than those who were not Black. Because creatinine comes from muscle, it was suspected that Black people had a higher muscle mass, and therefore higher creatinine levels. To compensate for this difference, rather than using data on muscle mass as a correction factor, researchers chose to use race as a proxy.
“You can imagine the problem: not all African Americans have a higher muscle mass than non-African Americans,” Dr. Djamali said.
Since race is a social construct, not a biological one, this assumption can lead to unintended consequences for Black patients.
When the formula includes race, it becomes possible that a Black patient’s kidney function will appear better than it really is, potentially delaying necessary care.
“If race is part of the formula, the main unintended consequence is that African Americans’ access to renal replacement therapy and in particular, kidney transplantation, can be delayed,” Dr. Djamali said.
Using this formula also reinforces erroneous assumptions about a biological basis of race.
“I think that’s something we see in medicine all too often, is becoming complacent with the status quo,” Dr. Darsie said.
This is why the UWSMPH and UW Health formed a ten-member multidisciplinary committee to implement a new approach to assess kidney function, without using race. Instead, they will use a confirmatory cystatin C-based GFR test as chronic kidney disease becomes more advanced and the specific GFR value will determine appropriate next steps in care.
While researchers are still trying to understand what accounts for the difference in GFR at the same creatinine level, this is an important first step towards achieving equity in medicine.
“We’re looking for accuracy, but we’re also looking for equitable methods, based on good science,” Dr. Darsie said.
The committee recommends that other medical centers follow suit.
“We strongly encourage all health systems to follow this example, and for everyone in the practice of medicine to intentionally engage in anti-racism efforts,” Dr. Djamali said.
Dr. Darsie adds, “I think that this is one tangible way that we’re trying to be better, and it’s such a small thing in the grand scheme of things, but it’s still something, and I think that’s worth acknowledging.”
- The problem with race-based medicine. TEDMED November 2015.
- Committee Members
- Amaka Achufusi, MBBS, Nephrology
- Brad Astor, PhD, Nephrology
- Marin Darsie, MD, Emergency Medicine and Neurological Surgery
- Arjang Djamali, MD, Nephrology
- Neetika Garg, MBBS, Nephrology
- Sarah A. Hackenmueller, PhD, Pathology and Laboratory Medicine
- Jonathan Jaffery, MD, Chief Population Health Officer
- Maha Mohamed, MD, Nephrology
- Melissa Roberts, MSN, RN, Service Line Director, Organ Donation and Transplant Services at UW Health
- Tripti Singh, MBBS, Nephrology
Above, from left: A representative group of committee members Tripti Singh, MD; Arjang Djamali, MD, MS; Marin Darsie, MD; and Sarah Hackenmueller, PhD, meet to discuss their recommendation to remove race from the GFR formula. Credit: Clint Thayer/Department of Medicine