Nov. 17, 2022
Mayo Clinic kidney transplant specialists feel hopeful to see another step toward racial equity for patients requiring transplants in the U.S. In 2022, the United Network for Organ Sharing (UNOS) announced transplant centers must use race-neutral listing criteria.
"U.S. kidney transplant leadership has been working hard to eliminate barriers and historical disadvantages for all patients requiring transplant, especially criteria by age, gender and race," says Naim S. Issa, M.D., a nephrologist and transplant specialist at Mayo Clinic. "This is a key step in achieving more-equitable criteria for all races, especially for Black people."
eGFR and previous listing disadvantages to Black patients
The kidney function formula that UNOS disallows now is the estimated glomerular filtration rate (eGFR). The eGFR estimates kidneys' capability to remove creatinine and thus kidney function, and it has been used to determine waitlist status. Mayo Clinic kidney transplant experts as well as other national kidney transplant leaders agree the eGFR has historically disadvantaged African Americans seeking kidney transplant.
Transplant centers often have employed kidney function estimate formulas such as the Chronic Kidney Disease Epidemiology Collaboration. These formulas include a Black race variable which increase eGFR values for this population and responds to a 1999 Annals of Internal Medicine publication demonstrating increased creatinine levels in the Black population versus the non-Black population. These formulas report higher eGFRs for Black people compared with people who are not Black, despite the equivalent characteristics other than race, indicates Dr. Issa. These race-based calculations can overestimate a Black patient's kidney function by up to 16%, according to an editorial in a 2019 issue of JAMA.
"The inclusion of race in the calculation of kidney function has been linked to disparities in care for African Americans, including delays in diagnosis of kidney disease and eligibility to be put on the waiting list for a kidney transplant," says Dr. Issa. "We hope the new UNOS requirement of a race-neutral formula to determine kidney transplant eligibility at all U.S. transplant centers will improve African Americans' transplant access and save lives."
Mayo Clinic's history of using alternative kidney function measurement
Notably, Mayo Clinic and some other transplant centers have not relied on the eGFR number. Instead, Mayo Clinic has directly measured patients' glomerular filtration rates to determine kidney function. But the lack of this measurement method's broad availability across laboratories nationally — not to mention its expense — has posed barriers for many transplant centers to use glomerular filtration rates, leading many medical professionals to use eGFR instead to determine transplant waiting list qualification, says Dr. Issa.
Racial disparities persist for Black individuals needing kidney transplant
While the UNOS formula change improves race neutrality in kidney transplant listing criteria, racial disparities remain an issue impacting access for Black patients. According to the National Kidney Foundation, African Americans are more than three times as likely to experience kidney failure than white individuals. And a 2020 Transplantation article identifies the Black population as less likely to be put on a kidney transplant waiting list. Further, a Kidney International 2016 publication indicates that once on a waiting list, Black patients often wait longer than white patients for kidney transplants.
African Americans are at high risk of kidney failure, partly due to elevated diabetes and high blood pressure rates, according to the National Institute of Diabetes and Digestive and Kidney Diseases. A 2008 Nature Genetics publication points to variation in a genetic locus, myosin heavy chain 9, for some individuals with Western African ancestry, accounting for increased risk of nondiabetic kidney disease. Apolipoprotein L1 genetic variants also account for elevated kidney disease risk, according to a 2015 Seminars in Nephrology publication. In addition, economic and social conditions play a role, as do lack of health care access and structural racism, according to a 2021 Harvard Health Publishing article.
"African Americans are markedly overrepresented among patients on dialysis and are less likely to be referred for or receive a kidney transplant," Dr. Issa says.
African American kidney donors and patient referrals encouraged
While the UNOS transplant policy change helps neutralize race in kidney transplant waiting list criteria, Dr. Issa and Mayo Clinic kidney transplant colleagues hope more people, especially Black individuals, will consider kidney donation.
Of the nearly 90,000 patients in the U.S. on the kidney transplant waiting list, more than one-third are Black patients. While organs are not matched based on race and ethnicity, individuals generally have a higher chance of matching with someone from a similar racial or ethnic background.
Mayo Clinic Transplant Center has one of the largest living-donor programs in the United States, welcoming new donor candidates and providing information for potential donors and their physicians on its website.
Mayo Clinic kidney transplant specialists also encourage physicians to refer patients with kidney disease to Mayo preemptively, prior to dialysis if possible, to increase survival time, which can be shortened by dialysis pretransplant.
For more information
Implementation notice: Requirement for race-neutral eGFR formulas in effect. United Network for Organ Sharing.
Levey AS, et al. A more accurate method to estimate glomerular filtration rate from serum creatinine: A new prediction equation. Annals of Internal Medicine.1999;130:461.
Eneanya ND, et al. Reconsidering the consequences of using race to estimate kidney function. JAMA. 2019;322:113.
Race, ethnicity & kidney disease. National Kidney Foundation.
Ku E, et al. Racial and ethnic disparities in kidney transplant access within a theoretical context of medical eligibility. Transplantation. 2020;104:1437.
Taber DJ, et al. Twenty years of evolving trends in racial disparities for adult kidney transplant recipients. Kidney International. 2016;90:878.
Race, ethnicity, & kidney disease. National Institute of Diabetes and Digestive and Kidney Diseases.
Kao WH, et al. MYH9 is associated with nondiabetic end-stage renal disease in African Americans. Nature Genetics. 2008;40:1185.
Dummer PD, et al. APOL1 kidney disease risk variants: An evolving landscape. Seminars in Nephrology. 2015;35:222.
Tucker JK. What's behind racial disparities in kidney disease? Harvard Health Publishing.
Living-donor transplantation. Mayo Clinic.
Refer a patient to Mayo Clinic.