Estimating glomerular filtration rate in children: evaluation of creatinine- and cystatin C-based equations

Background Glomerular filtration rate (GFR) estimated by creatinine- and/or cystatin C-based equations (eGFR) is widely used in daily practice. The purpose of our study was to compare new and old eGFR equations with measured GFR (mGFR) by iohexol clearance in a cohort of children with chronic kidney disease (CKD). Methods We examined 96 children (median age 9.2 years (range 0.25-17.5)) with CKD stages 1-5. A 7-point iohexol clearance (GFR7p) was defined as the reference method (median mGFR 66 mL/min/1.73 m.sup.2, range 6-153). Ten different eGFR equations, with or without body height, were evaluated: Schwartz.sub.bedside, Schwartz.sub.CKiD, Schwartz.sub.cysC, CAPA, LM.sub.REV, (LM.sub.REV + CAPA) / 2, FAS.sub.crea, FAS.sub.cysC, FAS.sub.combi, FAS.sub.height. The accuracy was evaluated with percentage within 10 and 30% of GFR7p (P10 and P30). Results In the group with mGFR below 60 mL/min/1.73 m.sup.2, the Schwartz.sub.cysC equation had the lowest median bias (interquartile range; IQR) 3.27 (4.80) mL/min/1.73 m.sup.2 and the highest accuracy with P10 of 44% and P30 of 85%. In the group with mGFR above 60 mL/min/1.73 m.sup.2, the Schwartz.sub.CKiD presented with the lowest bias 3.41 (13.1) mL/min/1.73 m.sup.2 and P10 of 62% and P30 of 98%. Overall, the Schwartz.sub.cysC had the lowest bias - 1.49 (13.5) mL/min/1.73 m.sup.2 and both Schwartz.sub.cysC and Schwartz.sub.CKiD showed P30 of 90%. P10 was 44 and 48%, respectively. Conclusions The Schwartz.sub.cysC and the combined Schwartz.sub.CKiD present with lower bias and higher accuracy as compared to the other equations. The Schwartz.sub.cysC equation is a good height-independent alternative to the Schwartz.sub.CKiD equation in children and can be reported directly by the laboratory information system. Clinical Trial Registration http://clinicaltrials.gov http://clinicaltrials.gov , Identifier NCT01092260, https://clinicaltrials.gov/ct2/show/NCT01092260?term=tondel&rank=2
Author(s): Cathrin L Salvador [sup.1] [sup.2] , Camilla Tøndel [sup.3] [sup.4] , Alexander D Rowe [sup.5] , Anna Bjerre [sup.6] , Atle Brun [sup.7] [sup.8] , Damien Brackman [sup.3] , [...]