B-276 Impact of Creatinine Methods on GFR Estimation and CKD Staging in Pediatric and Adult Populations
TL;DR
Differences between the enzymatic and Jaffe creatinine methods may lead to misclassification of CKD stage in children, particularly in infants, but not in adults, as all were classified with normal kidney function.
Abstract
Serum creatinine serves as the basis for estimating glomerular filtration rate (eGFR), a key parameter used to detect and monitor chronic kidney disease (CKD). Creatinine is mostly measured using either the alkaline picrate (Jaffe) or enzymatic methods. Variability between these assays can alter eGFR estimation and subsequent CKD classification, which may impact clinical management. This study compares eGFR estimates derived from plasma creatinine concurrently measured by the Abbott Jaffe and enzymatic methods to assess the clinical impact of assay selection on CKD classification in children and adult populations. A total of 195 residual plasma samples submitted for routine care were stratified by age group. Creatinine values measured by Jaffe and enzymatic methods (Alinity, Abbott Laboratories, USA) were collected for each sample. For patients <18 years of age, height recorded closest to the sample collection was obtained from the clinical chart. Estimated glomerular filtration rate (eGFR) was calculated using the 2021 CKD-EPI equation for adults (>18 years), the 2009 Bedside Schwartz equation for infants (< 1 year), and the CKiD Under 25 (CKiDU25) for individuals aged 1–18 years (pediatric population). The eGFR values were then used for CKD classification. Prism GraphPad was used for statistical analysis. P values for paired and unpaired comparisons between groups were calculated using Wilcoxon signed-rank test or Mann–Whitney U test, as appropriate. P value <0.05 was considered statistically significant. Among the 195 samples analyzed (81 infants, 86 pediatric, 28 adults), the median creatinine concentrations measured by the Jaffe method were significantly higher than the enzymatic method across all patients (0.48 vs 0.39; p < 0.0001), infants (0.41 vs 0.30; p < 0.0001), pediatric (0.56 vs 0.53; p < 0.0001) and adult populations (0.56 vs 0.50; p < 0.0001). Both relative and absolute bias between the two methods were significantly greater in the infant population than in the pediatric population (p < 0.0001), but did not differ significantly between pediatric and adult populations (p = 0.31). Median eGFR values were higher with the enzymatic method in the infant, pediatric, and adult populations (p < 0.0001). The Jaffe assay significantly overestimated CKD stage 3 in infants (70% vs 49%; p = 0.01) and stage 2 in pediatric patients (29% vs 13%; p = 0.014). No difference was observed in adults, as all were classified with normal kidney function (eGFR>90). Differences between the enzymatic and Jaffe creatinine methods may lead to misclassification of CKD stage in children, particularly in infants, but not in adults.