Performance of cystatin C-based equations in a pediatric cohort at high risk of kidney injury.

Background: Limited data exist on the performance of cystatin C-based glomerular filtration rate (GFR) equations in pediatric transplant recipients and other high-risk patients. The aim of our study was therefore to evaluate the performance of current cystatin C-based equations in this population.
Methods: This was a retrospective, cross-sectional study of 141 consecutive patients (58 % post-transplant) who received a nuclear medicine GFR (NucGFR) examination using (99m)Tc- diethylenetriaminepentaacetic acid at our institution. Subjects included children receiving liver, kidney or hematopoietic stem cell transplants and patients with oncologic or urologic disease. GFR estimates using published GFR estimating equations, including those based on cystatin C (Filler, Zappitelli, Larsson, Hoek, Rule and Le Bricon equations, respectively) and on both cystatin C and creatinine (Zappitelli, Bouvet and Schwartz equations, respectively), were evaluated and compared to the NucGFR measurement using Bland-Altman analysis.
Results: The mean NucGFR was 95 (interquartile range 76-111) ml/min/1.73 m(2). Of the cystatin C-based equations, the Rule, Hoek, Zappitelli and Schwartz (2009 CKiD equation) formulas provided the closest agreement to the NucGFR estimate. All other formulas overestimated the GFR in our cohort.
Conclusion: Cystatin C-based GFR formulas can provide an accurate estimation of NucGFR in a pediatric population with a high proportion of transplant recipients and oncology patients.