Performance of estimated glomerular filtration rate equations in Black living kidney donor candidates

Abstract

IntroductionNew estimated glomerular filtration rate (eGFR) equations using serum creatinine and/or cystatin C have been derived to eliminate adjustment by perceived Black ancestry. We sought to analyze the performance of newer eGFR equations among Black living kidney donor candidates.MethodsBlack candidates (n = 64) who had measured iothalamate GFR between January 2015 and October 2021 were included, and eGFR was calculated using race adjusted (eGFRcr2009 and eGFRcr‐cys2012) and race unadjusted (eGFRcys2012, eGFRcr2021, and eGFRcr‐cys2021) CKD‐EPI equations. Bias and accuracy were calculated.ResultsThe eGFRcr2021 equation had a negative bias of 9 mL/min/1.73 m2, while other equations showed a modest positive bias. Accuracy within 10% and 30% was greatest using the eGFRcr‐cys2021 equation. With the eGFRcr2021 equation, 9.4% of donors with an mGFR > 80 mL/min/1.73 m2 were misclassified as having an eGFR < 80 mL/min/1.73 m2. eGFR was also compared among 18 kidney donors at 6–24 months post‐donation. Post‐donation, the percentage of donors with an eGFR < 60 mL/min/1.73 m2 was 44% using the eGFRcr2021 equation compared to 11% using the eGFRcr‐cys2021 equation.ConclusionThe CKD‐EPICr2021 equation appears to underestimate true GFR in Black living donor candidates. Alternatively, compared to CKD‐EPICr2021, the CKD‐EPICr‐CysC2021 equation appears to perform with less bias and improved accuracy.