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

Abstract

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 51Cr-EDTA and used as the reference. We compared values of mGFR and estimated GFR (eGFR) by CKD-EPI equations based on sCr (eGFRCr) and on the combination of sCr and sCys (eGFRCr-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 m2. Mean eGFRCr and eGFRCr-Cys without race adjustment were 47.8 ± 30.1 ml/min/1.73 m2 and 46.4 ± 30.3 ml/min/1.73 m2, respectively. The corresponding P30 accuracy values were 79.0% and 83.0%. In the African Brazilian subgroup, values for mean mGFR and eGFRCr either without or with race adjustment were 49.8 ± 32.2 ml/min/1.73 m2, 50.4 ± 32.7 ml/min/1.73 m2, and 58.4 ± 37.9 ml/min/1.73 m2 (P<0.001 vs. mGFR), respectively. P30 accuracy values for eGFRCr 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.