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

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.

The study enrolled 960 individuals 18years 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.

The Korean CKD-EPI equation was as follows: male, serum creatinine (Scr) ≤80μmol/L, GFR=141×(Scr/0.9)(-0.642)×(0.993)(Age); male, Scr>80μmol/L, GFR=141×(Scr/0.9)(-1.128)×(0.993)(Age); female, Scr≤62μmol/L, GFR=144×(Scr/0.7)(-0.465)×(0.993)(Age); female, Scr>62μmol/L, GFR=144×(Scr/0.7)(-1.382)×(0.993)(Age). The mean bias (mL/min/1.73m(2)) 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.

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.