Task Force Recommends Universal Adoption of Race-Neutral Formulas—With Cystatin C if Available—to Estimate and Report Kidney Function
As part of a recent nationwide effort to re-evaluate the inclusion of race in clinical formulas, the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) convened a task force to examine glomerular filtration rate (eGFR) estimating equations in the United States.1 After a comprehensive review of 26 possible formulas, the Task Force recommended the use of a refitted race-neutral Chronic Kidney Disease Epidemiology Collaboration (CKD-EPIcr_R) equation in all laboratories. Key reasons for the formula’s selection include diversity in its development, acceptable performance characteristics, and availability for immediate adoption by laboratories.
While the performance of CKD-EPIcr_R is improved over that of other formulas, its accuracy in predicting measured GFR (especially in Black populations) remains less than optimal. Thus, the authors also recommend efforts to increase widespread availability of another filtration marker, serum cystatin C. Combining this result with serum creatinine increases accuracy of diagnosis and staging of chronic kidney disease.1
Recent studies support the use of cystatin C in determining eGFR, especially in situations where confirmation of GFR is needed.2, 3 However, wide adoption of cystatin C use will require policy and reimbursement updates as well as improvements in standardization and calibration. NKF has updated its online eGFR Calculator with the recommended race-neutral eGFR equation.
- Delgado C, Baweja M, Crews DC, et al. A unifying approach for GFR estimation: recommendations of the NKF-ASN Task Force on reassessing the inclusion of race in diagnosing kidney disease [published online ahead of print, 2021 Sep 22]. Am J Kidney Dis. 2021; S0272-6386(21)00828-3. doi:10.1053/j.ajkd.2021.08.003
- Hsu CY, Yang W, Parikh RV, et al. Race, genetic ancestry, and estimating kidney function in CKD. N Engl J Med. 2021;385(19):1750-1760. doi: 10.1056/NEJMoa2103753
- Inker LA, Eneanya ND, Coresh J, et al. New creatinine- and cystatin C-based equations to estimate GFR without race. N Engl J Med. 2021;385(19):1737-1749. doi:10.1056/NEJMoa2102953