Purpose: Analyze the accuracy of estimated glomerular filtration rate (eGFR) in pediatric renal transplant (Tx) patients (pts) using cystatin C, serum creatinine (SCr), and the combined cystatin C and SCr CKiD equation in comparison to iohexol clearance (iGFR), the gold standard.
Methods: Cystatin C (standardized Gentian), SCr (Jaffe and enzymatic) and iGFR were obtained from 17 renal Tx pts, 1-18 years old, with stable Tx function who presented for protocol biopsies (Bx). eGFR data were analyzed in terms of bias (difference between eGFR and iGFR), precision (variability of predictions around iGFR), and accuracy (proportion of estimates falling within 10 percent of iGFR). Secondary analyses evaluated the accuracy of cystatin C and SCr in pts with Bx-proven histological changes by Banff criteria (9 of 17 subjects); the effect of steroid use on cystatin C; comparing the Gentian cystatin C equation to other published cystatin C equations.
Results: The mean iGFR in our population was 95.9 +/- 24.6 ml/min/1.73m2. The eGFR equation using Gentian cystatin C was most accurate compared to SCr, CKiD equation, and other cystatin C eGFR equations. For example, using SCr (Jaffe), only 18% of the sample population and 22% of pts with changes on Bx yielded results within 10% of the iGFR. With cystatin C, 47% of the sample population and 67% of pts with changes on Bx had eGFR within 10% of iGFR. Similar trends were observed in a subgroup of patients on steroid-based immunosuppression (14 of 17 subjects).
Conclusions: The standardized Gentian cystatin C assay and equation appears to be the most accurate in predicting GFR in pediatric renal Tx pts, especially in those with perceived stable renal Tx function exhibiting changes on biopsy. It also seems to outperform several other cystatin C equations and worked well despite the fact that the majority of our patients were taking steroids, which are known to affect serum cystatin C concentrations.
Pizzo, H.: Grant/Research Support, Gentian Cystatin C Assay. Nguyen, J.: Grant/Research Support, Gentian Cystatin C Assay. Schwartz, G.: Grant/Research Support, Gentian Cystatin C Assay. Ettenger, R.: Grant/Research Support, Gentian Cystatin C Assay. Tsai, E.: Grant/Research Support, Gentian Cystatin C Assay.
To cite this abstract in AMA style:Pizzo H, Nguyen J, Schwartz G, Ettenger R, Tsai E. Comparison of Estimated Glomerular Filtration Rate Using Cystatin C Versus Creatinine in Pediatric Renal Transplant Patients [abstract]. Am J Transplant. 2013; 13 (suppl 5). https://atcmeetingabstracts.com/abstract/comparison-of-estimated-glomerular-filtration-rate-using-cystatin-c-versus-creatinine-in-pediatric-renal-transplant-patients/. Accessed July 30, 2021.
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