Validation of the EKFC equation for glomerular filtration rate estimation and comparison with the Asian-modified CKD-EPI equation in Chinese chronic kidney disease patients in an external study

Objectives The aim of this study is to determine whether new European Kidney Function Consortium (EKFC) equation is more applicable than Asian-modified CKD-EPI equation in clinical practice, having a higher accuracy in estimating GFR in our external CKD population. Methods We calculated estimated GFR(EKFC) and GFR(CKD-EPI) independently using the EKFC and Asian-modified CKD-EPI formulas, respectively. The clinical diagnostic performance of the two equations was assessed and compared by median bias, precision, accuracy (P (30)) and so on, using Tc-99m-DTPA dual plasma sample clearance method as a reference method for GFR measurement (mGFR). The equation that met the following targets was superior: (1) median bias within +/- 3 mL/min/1.73 m(2); (2) P (30) > 75%; and (3) better precision and 95% limits of agreement in Bland-Altman analysis. Results Totally, 160 CKD patients were recruited in our external cohort. GFR(EKFC) was highly related to mGFR, with a regression equation of GFR(EKFC)=mGFR x 0.87 + 5.27. Compared with the Asian-modified CKD-EPI equation, EKFC equation demonstrated a wider median bias (-1.64 vs. 0.84 mL/min/1.73 m(2), p < 0.01) that was within 3 mL/min/1.73 m(2) and not clinically meaningful. Furthermore, the precision (12.69 vs. 12.72 mL/min/1.73 m(2), p = 0.42), 95% limits of agreement in Bland-Altman analysis (42.4 vs. 44.4 mL/min/1.73 m(2)) and incorrect reclassification index of the two target equations were almost identical. Although, EKFC equation had a slightly better P (30) (80.0% vs. 74.4%, p = 0.01). Conclusions The overall performance of EKFC equation is acceptable. There is no clinically meaningful difference in the performance of the Asian-modified CKD-EPI and EKFC equations within the limits imposed by the small sample size.

Automated summary

The aim of this study was to determine whether the new European Kidney Function Consortium (EKFC) equation is more applicable than the Asian-modified CKD-EPI equation in estimating GFR in a clinical setting. The overall performance of the EKFC equation was found to be acceptable, with no clinically meaningful difference compared to the Asian-modified CKD-EPI equation within the limits of the small sample size.