Estimating glomerular filtration rate in children: evaluation of creatinine- and cystatin C-based equations
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).
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 m2, range 6–153). Ten different eGFR equations, with or without body height, were evaluated: Schwartzbedside, SchwartzCKiD, SchwartzcysC, CAPA, LMREV, (LMREV + CAPA) / 2, FAScrea, FAScysC, FAScombi, FASheight. The accuracy was evaluated with percentage within 10 and 30% of GFR7p (P10 and P30).
In the group with mGFR below 60 mL/min/1.73 m2, the SchwartzcysC equation had the lowest median bias (interquartile range; IQR) 3.27 (4.80) mL/min/1.73 m2 and the highest accuracy with P10 of 44% and P30 of 85%. In the group with mGFR above 60 mL/min/1.73 m2, the SchwartzCKiD presented with the lowest bias 3.41 (13.1) mL/min/1.73 m2 and P10 of 62% and P30 of 98%. Overall, the SchwartzcysC had the lowest bias − 1.49 (13.5) mL/min/1.73 m2 and both SchwartzcysC and SchwartzCKiD showed P30 of 90%. P10 was 44 and 48%, respectively.
The SchwartzcysC and the combined SchwartzCKiD present with lower bias and higher accuracy as compared to the other equations. The SchwartzcysC equation is a good height-independent alternative to the SchwartzCKiD equation in children and can be reported directly by the laboratory information system.
Clinical Trial Registration
ClinicalTrials.gov, Identifier NCT01092260, https://clinicaltrials.gov/ct2/show/NCT01092260?term=tondel&rank=2
KeywordsGlomerular filtration rate Child Chronic kidney disease Renal function Cystatin C
We wish to express our gratitude to the pediatric study nurses Mai Britt Lynum (Oslo University Hospital), Hildur Grindheim, and Renathe Håpoldøy (Haukeland University Hospital) for their technical assistance with the sample collection and to the laboratory engineer Kjersti Carstensen for the iohexol analyses (Haukeland University Hospital). The study was supported by grants from the Health Trust of Western Norway, The Norwegian Society of Nephrology, Haukeland University Hospital, and Oslo University Hospital.
Compliance with ethical standards
The authors have no financial relationships relevant to this article to disclose.
Conflict of interest
The authors declare that they have no conflict of interest.
The study was approved by the Regional Ethics Committee of Western Norway and an informed consent form was obtained by all patients and/or their designees. The study was performed in accordance with the Declaration of Helsinki.
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