The Mount Sinai Health System has switched from the Modification of Diet in Renal Disease (MDRD) equation to the more accurate Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation to calculate estimated glomerular filtration rate (eGFR) and, as part of the change, eliminated the race-based coefficient as of December 8, 2020.
The MDRD and CKD-EPI equations both include a coefficient that reports different eGFR values for Black and non-Black patients, based on the assumption that Black patients have higher muscle mass. But the coefficient is controversial and its use in eGFR equations has been linked to delays in referral to specialist care, later qualification for kidney transplantation, and poorer outcomes among Black patients.
Initially developed in 2009, the CKD-EPI equation is based on serum creatinine, age, and assigned sex at birth. Accuracy can be further improved when using this equation by incorporating measurement of cystatin C. An individualized and multidisciplinary approach will be used when interpreting eGFR for transgender and gender-expansive patients, and the height/creatinine-based Schwartz formula will be used for patients younger than 19.
“We recognize that the formulae we use to estimate kidney function are flawed and that there are limitations in equating race with ancestry and genetic predisposition, the latter being concepts we should preferably be using in the clinical setting,” says Kirk Campbell, MD, Associate Professor of Medicine (Nephrology) at the Icahn School of Medicine at Mount Sinai. “Our decision to remove this race coefficient in estimating GFR reflects both an analysis of published data and Mount Sinai’s commitment to equity in the care we provide our patients.”
The coefficient has been a topic of debate among Mount Sinai faculty for some time and became the subject of a petition launched by first-year Icahn School of Medicine students Carina Seah and Paloma Orozco Scott in the summer of 2020.
“What we are saying is that race is not biological, it is not found in the kidney, and therefore it should be removed from the equation for kidney function.”
Paloma Orozco Scott, medical student
“There was a physiology lecture by Staci Leisman, MD, called ‘Can Math Be Racist?’ that included the history of the MDRD equation, and my reaction was, ‘This is the most eye-opening and shocking lecture I have ever received,’” Ms. Seah recalls. “As medical students, we learn that race is sociopolitical and not biological, and the fact this equation existed and was still being used, including at Mount Sinai, was unbelievable to me, so we started a petition to change that.”
Ms. Orozco Scott notes there was little pushback to the petition, but there were concerns related to the removal of the correction, specifically the fear that it might result in scientists and physicians not studying or considering the effects of race and racism on their patients. “We are aware of this fear and want to guard against that occurring, as a science that does not grapple with race at all does not do justice to the reality of patients,” Ms. Orozco Scott says. “What we are saying is that race is not biological, it is not found in the kidney, and therefore it should be removed from the equation for kidney function.”
One early signatory was Dr. Leisman, who developed the lecture in 2015 after a student expressed concerns that the correction was racist. “I think these actions speak both to Mount Sinai’s intent to engage in discussions about racism and the activism and fierce advocacy by our medical students. They push us as an institution to ensure what we are teaching is accurate, anti-racist, and current, and will hold us accountable when they observe care that marginalizes or oppresses vulnerable populations,” says Dr. Leisman, who is Associate Professor of Medicine (Nephrology) at the Icahn School of Medicine.
The change does present some challenges. LabCorp, which processes eGFR for some Mount Sinai Doctors Faculty Practice offices, has indicated it will wait for recommendations from the National Kidney Foundation/American Society of Nephrology national task force before removing the race coefficient, so patient results delivered by LabCorp will be used as is for now, Dr. Campbell said. Follow-ups are also being conducted with clinical specialties such as oncology, radiology, and surgery to ensure that the change in reporting will not have any negative impacts on medical decisions or patient outcomes.
“This is an interim step,” Dr. Campbell cautions. “Based on excellent work being done at the national and international level, there eventually will be new tools that will be more accurate in estimating GFR. When that happens, we will adopt them. But our intent in taking this action is not to entirely remove consideration of race, as that may result in harm to those who are most vulnerable. Where differences exist, whether due to genetic or socioeconomic factors, rigorous quality assessment must be performed to understand their underpinnings so we can take appropriate steps to reduce disparities in care delivery.”
Kirk Campbell, MD
Professor of Medicine (Nephrology)