Race, ethnicity eGFR adjustments 'significantly overestimated' GFR among Black patients
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Calculations for eGFR were closer to measured GFR without adjustments for race, which suggested adjusting eGFR for race could lead to underdiagnosis of chronic kidney disease among Black patients in the United Kingdom, according to results.
Rouvick Gama, MD, presented the findings at ASN Kidney Week, which was held as a virtual event.
The two main equations used to calculate GFR, the modification of diet in renal disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), both have correction factors for race (1.212 and 1.159, respectively), Gama said. Of the 1,628 U.S. patients whose data the MDRD was derived from, only 8% were Black.
“People of Black ethnicity have a higher risk [for] CKD, increased progression of disease and have a higher incidence of end-stage kidney disease. Therefore, accurate measurement of GFR is important,” Gama said. “Recent studies from Africa, however, suggest that estimated GFR equations more accurately reflect [measured] GFR without the ethnicity correction factor.
“Therefore, inappropriate use of [these] ethnicity-adjusted eGFR equations could further contribute to recognized ethnicity-related health inequities in CKD,” Gama said.
To assess the accuracy of ethnicity adjustments in eGFR equations, Gama and colleagues conducted a 10-year, single-center observational cohort study that compared measured-GFR with eGFR calculations that were adjusted for race and eGFR calculations that were not adjusted for this. Exclusion criteria were albumin of less than 30 g/L, ESDK, liver disease, minors and patients whose ethnicity was not Black, white or “mixed race.” Patients had a mean age of 54 years and a mean BMI of 27 kg/m2, which Gama said was “comparable between Black and white ethnicity,” and 15.6% were Black.
“In Black patients, CKD-EPI and MDRD eGFR equations significantly overestimated GFR compared to white [patients] (P <.001) but without ethnicity correction, factor estimates were considerably improved (P <.001),” the investigators wrote.
Gama said the effect was most significant among Black patients and patients whose eGFR was more than 60 mL/min/1.73 m2. Among Black patients whose eGFR was more than 60 mL/min/1.73 m2, the mean measured GFR was 87.7 mL/min/1.73 m2 (CKD-EPI: adjusted, 108.1 mL/min/1.73 m2 vs. unadjusted, 93.3 mL/min/1.73 m2; MDRD: adjusted, 107.7 mL/min/1.73 m2 vs. unadjusted, 88.8 mL/min/1.73 m2).
Gama said the results are similar to previous studies conducted in Africa and Europe.
“In summary, we found the CKD-EPI and MDRD equations, when adjusted, led to an overestimation of eGFR compared to measured GFR in a Black ethnicity U.K. population,” Gama said. “This may increase the risk of delaying diagnosis and delay recognition severity in this population in the U.K.”
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Gama R, et al. FR-OR-14. Presented at: ASN Kidney Week. Oct. 22-25, 2020 (virtual meeting).
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