Development and validation of the Korean version of CKD-EPI equation to estimate glomerular filtration rate

Background: The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation was derived mostly from Caucasian, African-American, and Hispanic populations, whereas Asian populations were excluded. The aim of this study was to develop and validate a Korean version of the CKD-EPI equation. Methods: The study enrolled 960 individuals 18 years old and older who underwent chromium-51-ethylenediaminetetraacetic-acid-based glomerular filtration rate (GFR) measurements. They were divided randomly into two groups: a development set (n = 768, 80%) and a validation set (n = 192, 20%). The Korean CKD-EPI equation was developed using a non-linear mixed-effect model. The performance of the equation was evaluated by calculating the bias (estimated GFR-measured GFR). The ±. 10% (P10) and ±. 30% (P30) accuracies and root mean square errors (RMSEs) of the original and Korean CKD-EPI equations were compared. Results: The Korean CKD-EPI equation was as follows: male, serum creatinine (Scr) ≤80 μmol/L, GFR = 141 × (Scr/0.9)^-0.642 × (0.993)^Age; male, Scr > 80 μmol/L, GFR = 141 × (Scr/0.9)^-1.128 × (0.993)^Age; female, Scr ≤ 62 μmol/L, GFR = 144 × (Scr/0.7)^-0.465 × (0.993)^Age; female, Scr > 62 μmol/L, GFR = 144 × (Scr/0.7)^-1.382 × (0.993)^Age. The mean bias (mL/min/1.73 m²) of the original CKD-EPI equation was -3.0 ± 13.5 and that of the Korean CKD-EPI equation -2.3 ± 13.3. The P10 and P30 of the original CKD-EPI equation were 33.9% and 82.8%; for the Korean CKD-EPI equation, the corresponding values were 35.4% and 85.9%. The RMSEs of the original and Korean CKD-EPI equations were 13.7 and 13.5, respectively. Conclusions: The overall analytical performance of the Korean CKD-EPI equation was equivalent to that of the original CKD-EPI equation. The original CKD-EPI equation is therefore also valid for the Korean population.