New evidence further confirms that use of the race coefficient when calculating estimated glomerular filtration rate (eGFR) in Black patients with chronic kidney disease (CKD) leads to systematic under-identification of severely decreased renal function.
This means Black patients miss out on timely treatment and may end up waiting years longer than others to be listed for kidney transplant.
Analysis of 1658 self-identified Black patients included in the US Chronic Renal Insufficiency Cohort database showed that using the race coefficient overestimated the actual eGFR rate by an average of more than 3 mL/min/1.73m2.
Eliminating the race modifier would have increased the number of Black patients with an eGFR that fell below 20 mL/min/1.73m2 — the point at which individuals are eligible for kidney transplant and listing — by more than a third during a median follow-up of 4 years, and would have hastened the median time by which patients reached this endpoint by almost 2 years.
“Be Cautious“ When Using Race Modifier
The new findings “suggest that nephrologists and transplant programs should be cautious” about using the race modifier to calculate eGFR in Black patients, the authors write.
The biases produced by the race modifier “while numerically modest may be associated with delays in potential pre-emptive transplant referral and eligibility among Black patients with CKD,” write Leila R. Zelnick, PhD, Division of Nephrology, University of Washington, Seattle, and colleagues in their article published online January 14 in JAMA Network Open.
Writing in an invited commentary, L. Ebony Boulware, MD, of Duke University School of Medicine, Durham, North Carolina, and colleagues agree.
These results suggest that removing the race coefficient from the prevailing formula for calculating eGFR — the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation — “could avert potential systematic delays imposed on Black individuals’ receipt of transplant care by several years,” they note.
This new research “provides evidence to support universal removal of the Black race coefficient from the eGFR equation,” they add, a step that would help in “rectifying longstanding transplant inequities for Black individuals.”
This latest work confirms findings published in 2020 that showed a third of more than 2000 African Americans included in an academic health system database would have been reclassified to a more severe stage of CKD if their eGFR calculated with the CKD-EPI formula had not included the race modifier.
Race-Modified eGFR Conflicts With Highly Reliable Standard
In the study by Zelnick and colleagues, among the 1658 people examined in the current study who self-identified as Black, 311 underwent GFR assessment based on iothalamate clearance, a method considered highly reliable for measuring GFR and the standard used to create the CKD-EPI formula for eGFR.
Analysis showed that the CKD-EPI formula with the race coefficient produced an average 3.1 mL/min/1.73m2 increase in eGFR compared with the GFR measured by iothalamate clearance, they report.
Their calculations also showed that among the 1616 Black patients who began with an eGFR of at least 20 mL/min/1.73m2, 29% had their renal function drop below the threshold during follow-up. This incidence rate spiked by 35% when the race coefficient got dropped.
“Even a delay of 1 year for referral [for kidney transplant] can have a significant effect on a patient’s life,” the authors write.
In 2020, the National Kidney Foundation and American Society of Nephrology organized a task force to make recommendations on the use of a race modifier when calculating eGFR. Release of those recommendations remains pending as of mid-January 2021, but is expected soon.
Also in 2020, some US health systems announced they had eliminated routine reporting of eGFR using the race modifier or strongly discouraged its use. This included the Mass General Brigham system in Boston, the University of Washington system in Seattle, and the Vanderbilt University Medical Center system in Nashville, as reported by Medscape Medical News.
Zelnick and Boulware have reported no relevant financial relationships.