One approach to lessening racial inequity in access to kidney transplants could be to allow Black patients onto the transplant waiting list at a higher level of estimated glomerular filtration rate (eGFR) than is currently needed to qualify, according to a study published in JASN.
Patients are normally eligible to be added to the kidney transplant waiting list when their eGFR drops to 20 mL/min per 1.73 m2, but the study authors estimated that registering Black people on the waitlist “as early as an eGFR of 24–25 mL/min per 1.73 m2 might improve racial equity in accruable wait time prior to [end stage kidney disease (ESKD)] onset.”
The study is part of the movement that gained great momentum last year to evaluate racial disparities in kidney care and in particular, the use of a race factor in most GFR estimating equations. As part of this effort, ASN partnered with the National Kidney Foundation (NKF) to form a Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Diseases that is expected to issue recommendations imminently.
The study, “Racial Disparities in Eligibility for Preemptive Waitlisting for Kidney Transplantation and Modification of eGFR Thresholds to Equalize Waitlist Time,” used data from the Chronic Renal Insufficiency Cohort (CRIC) Study, a multi-center observational cohort in the United States that enrolled participants between 2003 and 2008 and has followed them annually at in-person visits ever since. CRIC participants self-report their race. The authors used the 2012 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine-based eGFR equation to rate kidney function to construct a study cohort of patients eligible for waitlist registration. They then analyzed the effects of three different estimating equations on a study cohort of patients eligible for the waitlist. Two of the equations include a race factor (the 2012 CKD-EPI creatinine-based equation and a 2012 eGFR creatinine- and cystatin-C-based equation) and one that does not include a race adjustment (the 2012 CKD-EPI cystatin-C-based equation).
In the case of each equation, they found that Black people experienced a 31%–35% shorter time than Whites between reaching the 20 mL/min eGFR that made them eligible for the waiting list and the onset of ESKD and initiation of dialysis. They then calculated the level of kidney function at which Black patients would need to be added to the waitlist to equalize the potential wait times among Black and White patients using the different equations.
“Regardless of which equation we used to estimate kidney function, Black patients had less potential time available for waitlist registration than White patients,” according to lead author Elaine Ku, MD, MAS, director of the nephrology transition clinic at the University of California San Francisco. “Our results suggest that it may not solely be the race term itself in the existing GFR estimating equations that leads to racial disparities in access to the kidney transplant waitlist. We found that Black individuals have faster progression of their kidney disease than White individuals between the time when they would meet eligibility criteria for waitlist registration and onset of need for dialysis, which may contribute to racial disparities in preemptive waitlist access. We found that the use of a higher kidney function to allow for earlier eligibility for waitlisting in Blacks could theoretically reduce the racial disparity in time spent in the advanced stages of chronic kidney disease.”
Gabriel M. Danovitch, MD, chair of nephrology and renal transplantation at the David Geffen School of Medicine at UCLA, questioned the wisdom of changing eligibility criteria in this way: “I’m not comfortable with the idea that certain ethnic groups, by virtue of what is typically their self-identification as part of a group, would automatically be given some advantage in getting on the transplant list. It could easily be gamed by virtue of self-identification [or] by transplant staff. I think we should be more concerned with the basic issues, [which are] getting the best care for people who need it and doing our best to understand why African Americans are at increased risk of having kidney disease and addressing it.”
Mallika L. Mendu, MD, MBA, assistant professor at Harvard Medical School and a member of the NKF-ASN Task Force, said she agreed with the study’s “conclusion that the Black race modifier included in the CKD-EPI equation is not sufficient to explain disparities between Black and White patients in terms of transplantation. We need investment in strategies to address disparities across kidney disease care delivery for vulnerable patient populations, particularly Black, LatinX, and Native American patients. I’m hopeful that the current discussion about the importance of health equity among patients with kidney disease will move us in that direction.”
All three experts said they await the task force’s recommendations. “I think our data are informative for the NKF-ASN Task Force regarding the role of race and GFR estimation as it relates to transplant care, though we would emphasize that our study was done in a theoretical context,” Ku said.
