No Race-Ethnicity Adjustment in CKD-EPI Equations Is Required for Estimating Glomerular Filtration Rate in the Brazilian Population

BACKGROUND: Glomerular filtration rate (GFR) is usually estimated from equations using serum creatinine (sCr), with adjustment for gender, age, and race (black or nonblack). The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) is the preferred equation for adults, but it was validated for the United States population. We intended to evaluate if the race-ethnicity adjustment proposed for the sCr-based CKD-EPI equations is appropriate for the Brazilian population. METHODS: CKD outpatients had blood samples collected for determination of sCr and serum cystatin C (sCys) levels. GFR was measured (mGFR) by plasma clearance of (51)Cr-EDTA and used as the reference. We compared values of mGFR and estimated GFR (eGFR) by CKD-EPI equations based on sCr (eGFR(Cr)) and on the combination of sCr and sCys (eGFR(Cr-Cys)). For African Brazilian patients, eGFR was calculated either without or with race adjustment. Accuracy was considered acceptable if the difference between the values of eGFR and mGFR was ≤30% (P30). RESULTS: 100 patients were enrolled (58 ± 14 years, 46% male, 39% white and 61% African Brazilian). Mean mGFR was 46.7 ± 29.2 ml/min/1.73 m(2). Mean eGFR(Cr) and eGFR(Cr-Cys) without race adjustment were 47.8 ± 30.1 ml/min/1.73 m(2) and 46.4 ± 30.3 ml/min/1.73 m(2), respectively. The corresponding P30 accuracy values were 79.0% and 83.0%. In the African Brazilian subgroup, values for mean mGFR and eGFR(Cr) either without or with race adjustment were 49.8 ± 32.2 ml/min/1.73 m(2), 50.4 ± 32.7 ml/min/1.73 m(2), and 58.4 ± 37.9 ml/min/1.73 m(2) (P < 0.001 vs. mGFR), respectively. P30 accuracy values for eGFR(Cr) either without or with race adjustment were 75.4% and 67.2%, respectively. CONCLUSIONS: The use of CKD-EPI equations without race-ethnicity adjustment seems more appropriate for the Brazilian population.