Comparison of using glomerular filtration rate estimation equations in children with chronic kidney disease

Objective To compare the applicability of eight equations for estimating glomerular filtration rate (eGFR) in children. Methods From January 2016 to December 2021, clinical data were reviewed for 150 hospitalized CKD children aged 1-18 year. And Gates method of ^99mTc-DTPA renal dynamic imaging was employed as a gold standard and measured GFR recorded as mGFR (measured GFR). Bias, precision and accuracy of each estimation equation were compared. With the cutoffs of age of 13 years and mGFR=60 mL·min^-1·(1.73 m²) ^-1, the applicability of each equation in each group was examined hierarchically. Results Median age was 15(13, 17) years. Values of serum creatinine (Scr) and cystatin C (Cys C) were 67.0 (52.1, 91.9) μmol/L and 1.13 (0.86, 1.67) mg/L respectively and mGFR was (111.29±54.80) mL·min^-1·(1.73 m²) ^-1. GFR level was overestimated by CAPA and CKD-EPI-Scr equations at an overall level. Counahan-Barratt's P30 accuracy was the highest (64.7%) and FAS and CKiD equations had the highest P10 accuracy (both 22.7%). In children aged ≤ 13 years, CKD-EPI-Scr equation overestimated GFR (a bias of 0.94) and decent precision was achieved with the highest accuracy (P30 of 73.2%). For children aged <13 years, FAS equation had the optimal bias (-3.44); LMR18 equation had the optimal precision with the highest P30 accuracy (73.4%) and FAS equation yielded the highest P10 accuracy (24.7%). Among children with mGFR <60 mL·min^-1·(1.73 m²) ^-1, Counahan-Barratt equation offered the optimal bias, CKiD equation had the optimal precision and CKiD and Counahan-Barratt equation yielded the highest P30 accuracy (47.6%). In mGFR ≥ 60 mL·min^-1·(1.73 m²) ^-1group, CKD-EPI-Scr equation offered optimal bias and precision; in terms of accuracy, Counahan-Barratt equation yielded the highest P30 (67.4%) and FAS equation had the highest P10 (23.3%). Conclusion In CKD children, CKiD and Counahan-Barratt equations outperformed other equations at an overall level. In young children, CKD-EPI-Scr equation is more accurate; for older children, LMR18 and FAS all-age formulas are recommended for assessing GFR.