Diagnostic Accuracy of Eight Estimated Glomerular Filtration Rate Equations for Assessing Kidney Function in Korean...

Estimated glomerular filtration rate (eGFR) in children is typically calculated using the Schwartz equation. Recently developed equations, such as the Chronic Kidney Disease in Children Under 25 (CKiD U25) and the European Kidney Function Consortium (EKFC) formulas are increasingly used; however, validation studies in Korean pediatric populations remain limited. We compared the performance of eight eGFR equations (including the CKiD U25, EKFC, updated bedside Schwartz, and Schwartz cystatin C equations) using data from Korean children.

We retrospectively analyzed data from 221 pediatric patients (aged 2-18 yrs) who underwent ⁵¹Cr-EDTA-based measured GFR (mGFR) assessment, along with serum creatinine and cystatin C testing, at Asan Medical Center, Seoul, between 2010 and 2019. Eight eGFR equations were evaluated. Performance metrics assessed included bias, accuracy [mean absolute percentage error (MAPE) and percentage of estimates within 30% (P30), 20% (P20), and 10% (P10) of mGFR], precision (root mean square error), correlation coefficients (r), and agreement (overall concordance rate and Lin's concordance correlation coefficient).

Bias (mL/[min · 1.73 m²]) was lowest for CKiD U25_cys (1.6), EKFC_cys (-1.8), and CKiD U25_cr-cys (2.3). EKFC_cr showed the highest P30 (81.0%); however, the combined equations (EKFC_cr-cys, 80.5%; CKiD U25_cr-cys, 74.7%) demonstrated comparable P30 values with lower bias and more consistent performance across subgroups. Under stricter accuracy thresholds (P10, P20, and MAPE), the combined equations outperformed the other formulas. Correlation and concordance with mGFR were also highest with the combined equations.

Creatinine-cystatin C-based equations can aid in providing more accurate kidney function assessments in Korean children.