Impact of Applying the CKD-EPI 2021 Formula Compared to CKD-EPI 2009 for the Calculation of Estimated Glomerular Filtration Rate in a Spanish Tertiary Hospital

Background: Throughout the years, the stage of chronic kidney disease (CKD) has been classified according to the Kidney Disease: Improving Global Outcomes (KDIGO) guideline, using equations to calculate the estimated glomerular filtration rate (eGFR). The 2009 CKD-EPI equation is the one currently used, but there is a new version from 2021 that eliminates the race correction factor. In this study, we will compare both equations. Methods: Sex, age, and serum creatinine data from 64 819 patients were gathered. Glomerular filtration (GF) was estimated using both CKD-EPI equations based on sex and serum creatinine (sCr) value. Concordance was analyzed using the kappa index and Bland-Altman graphical method. Results: The mean eGFR for males with sCr > 0.90 mg/dL was 58 +/- 22 according to the 2009 CKD-EPI and 61 +/- 24 according to the 2021 CKD-EPI; for males with sCr <= 0.90 mg/dL, the eGFR was 94 +/- 11 according to 2009 CKD-EPI and 98 +/- 9 for the 2021 equation. For females with sCr values of >0.70 mg/dL, the mean eGFR was 60 +/- 22 for the 2009 CKD-EPI and 64 +/- 23 for the 2021 CKD-EPI. For females with sCr <= 0.70 mg/dL, the eGFR was 95 +/- 11 for the 2009 CKD-EPI and 99 +/- 10 for the 2021 CKD-EPI. The percentages of reclassified patients were 16%, 23%, 17%, and 22% for males with sCr >0.90, sCr <= 0.90, and females with sCr > 0.70 and <= 0.70 mg/dL, respectively.<br /> Conclusion: We found that the 2021 CKD-EPI equation, applied to our population, significantly increases the eGFR values, which causes a meaningful number of people to undergo a reclassification to a less severe of CKD.