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
2
, range 6–153). Ten different eGFR equations, with or without body height, were evaluated: Schwartz
bedside
, Schwartz
CKiD
, Schwartz
cysC
, CAPA, LM
REV
, (LM
REV
+ CAPA) / 2, FAS
crea
, FAS
cysC
, FAS
combi
, FAS
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
2
, the Schwartz
cysC
equation had the lowest median bias (interquartile range; IQR) 3.27 (4.80) mL/min/1.73 m
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
2
, the Schwartz
CKiD
presented with the lowest bias 3.41 (13.1) mL/min/1.73 m
2
and P10 of 62% and P30 of 98%. Overall, the Schwartz
cysC
had the lowest bias − 1.49 (13.5) mL/min/1.73 m
2
and both Schwartz
cysC
and Schwartz
CKiD
showed P30 of 90%. P10 was 44 and 48%, respectively.
Conclusions
The Schwartz
cysC
and the combined Schwartz
CKiD
present with lower bias and higher accuracy as compared to the other equations. The Schwartz
cysC
equation is a good height-independent alternative to the Schwartz
CKiD
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...

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

10.1007/s00467-018-4067-3