Accuracy of the New Creatinine-based Equations for Estimating Glomerular Filtration Rate in Koreans

Background: New creatinine-based estimated glomerular filtration rate (eGFR) equations, including the 2021 Chronic Kidney Disease Epidemiology Collaboration (2021 CKD-EPI) and European Kidney Function Consortium (EKFC) equations, have been introduced recently. We assessed the performance of the 2021 CKD-EPI and EKFC equations in the Korean population. Methods: We analyzed 1,654 Korean patients aged ≥18 years who underwent chromium-51-ethylenediamine tetraacetic acid GFR measurements (mGFR). Bias (eGFR–mGFR), root mean square error (RMSE), and proportion of eGFR within 30% of mGFR (P30) of the 2009 CKD-EPI, 2021 CKD-EPI, and EFKC equations were compared. The concordance rate between eGFR and mGFR categories was evaluated. Both eGFR and mGFR categories were classified into six groups: ≥90, 89–60, 59–45, 44–30, 29–15, and <15 mL/min/1.73 m². Results: The median bias (mL/min/1.73 m²) was 1.8 for the 2009 CKD-EPI equation, 4.8 for the 2021 CKD-EPI equation, and –0.3 for the EKFC equation. The P30 and RMSE were 78.2% and 17.0 for the 2009 CKD-EPI equation, 75.6% and 17.4 for the 2021 CKD-EPI equation, and 80.0% and 16.7 for the EKFC equation, respectively. The overall GFR category concordance rate between eGFR and mGFR was 63.4% for the 2009 CKD-EPI equation, 60.5% for the 2021 CKD-EPI equation, and 61.0% for the EKFC equation. Conclusions: Among the three eGFR equations, the EKFC equation had the smallest bias and highest P30 in Koreans. The 2009 CKD-EPI equation had a lower bias than the 2021 CKD-EPI equation.