Eliminating Race from Kidney Function Assessments

Patient and doctor discussing kidney test results

A joint task force established by the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) has called for all labs in the U.S. to estimate kidney function using a new formula that does not include race as part of its equation. 

Established in 2020, the task force reviewed how race was used in the calculation of estimated glomerular filtration rates (eGFR), which are a measurement of kidney function. The task force found that use of race in the equation led to racial disparities in kidney care and other health care decisions that take GFR into consideration.

In light of this, the task force developed a new formula: the eGFR 2021 CKD EPI equation. The new equation measures kidney function without factoring in race, and it is readily available to all labs in the U.S. The task force is now asking labs to use the new equation in order to provide unbiased and accurate eGFR. 

GFR is estimated regularly to check on kidney health and determine how well the kidneys are filtering the blood. The measurement can also be used in screening for, diagnosing, or monitoring kidney disease. GFR is commonly calculated with the results from a creatinine blood test. Sometimes the results from a cystatin C test are used instead or to verify results. Levels in these tests can be affected by factors such as a person’s age, sex and body weight. 

Previously, race was included in eGFR because of the incorrect presumption that race inherently impacts muscle mass, creatinine metabolism, and other factors of kidney function. Creators of an eGFR equation widely used today believed that African Americans had naturally higher kidney function. As a result, they included a multiplication factor in their equation based on race.

The use of race in eGFR has been questioned for a number of reasons. Blacks are disproportionately affected by kidney disease. Chronic kidney disease affects 16% of non-Hispanic Black Americans. Even though Blacks only make up 13% of the population, 35% of people in the U.S. with kidney failure are Black. Blacks are also more than three times more likely to develop kidney failure than Whites. 

The eGFR calculators that factor in race likely underestimate the prevalence of kidney dysfunction in Black patients. Consequently, Blacks may miss out on early diagnosis and monitoring and receive delayed treatment, leading to negative health outcomes. 

Furthermore, the terms Black and White were not clearly defined in the development of previous eGFR equations. The lack of definitions, along with a growing number of multiracial or mixed-race Americans, calls into question the use of race in measuring kidney function and in medical decision-making overall. 

The lack of race in the new eGFR 2021 CKD EPI equation accounts for a more diverse population in the U.S. 

In addition to implementing the new equation, the task force also recommends increasing regular use of cystatin C testing to confirm eGFR results for screening adults at risk for kidney disease or monitoring those who have kidney disease. Testing both creatinine and cystatin C allows for more accurate evaluations, especially when confirming kidney disease. Using results from both tests can lead to more informed clinical decision-making. 

The task force and other experts call for further research into markers of kidney disease that are not impacted by age, sex, or race. They believe such research can help make kidney function assessments more accurate and less biased, and help promote equitable health care. 

Sources

Delgado, C., Baweja, M., Crews, D. C., Eneanya, N. D., Gadegbeku, C. A., Inker, L. A., Mendu, M. L., Miller, W. G., Moxey-Mims, M. M., Roberts, G. V., St. Peter, W. L., Warfield, C., & Powe, N. R. (2021). A unifying approach for GFR estimation: Recommendations of the NKF-ASN task force on reassessing the inclusion of race in diagnosing kidney disease. American Journal of Kidney Diseases. Published. https://www.ajkd.org/article/S0272-63862100828-3/fulltext 

Delgado, C., Baweja, M., Burrows, N. R., Crews, D. C., Eneanya, N. D., Gadegbeku, C. A., Inker, L. A., Mendu, M. L., Miller, W. G., Moxey-Mims, M. M., Roberts, G. V., St. Peter, W. L., Warfield, C., & Powe, N. R. (2021). Reassessing the inclusion of race in diagnosing kidney diseases: An interim report from the NKF-ASN task force. Journal of the American Society of Nephrology, 32(6), 1305–1317. https://jasn.asnjournals.org/content/32/6/1305 

National Kidney Foundation. (2021). eGFR calculator. Retrieved October 22, 2021. https://www.kidney.org/professionals/kdoqi/gfr_calculator 

Braun, L., Wentz, A., Baker, R., Richardson, E., & Tsai, J. (2021). Racialized algorithms for kidney function: Erasing social experience. Social Science & Medicine, 268, 113548. https://pubmed.ncbi.nlm.nih.gov/33308910/ 

Centers for Disease Control and Prevention. (2021, March 4). Chronic kidney disease in the United States, 2021. Retrieved October 22, 2021. https://www.cdc.gov/kidneydisease/publications-resources/ckd-national-facts.html 

National Institute of Diabetes and Digestive and Kidney Diseases. (2014, March). Race, ethnicity, & kidney disease. Retrieved October 22, 2021. https://www.niddk.nih.gov/health-information/kidney-disease/race-ethnicity 

Vyas, D. A., Eisenstein, L. G., & Jones, D. S. (2020). Hidden in plain sight — Reconsidering the use of race correction in clinical algorithms. New England Journal of Medicine, 383(9), 874–882. https://pubmed.ncbi.nlm.nih.gov/32853499/