Comparison of estimated and measured GFR in pediatric CKD patients transitioning from adolescence to adulthood: results from KNOW-PedCKD

Abstract

Background Accurate estimation of glomerular filtration rate (eGFR) is essential for managing pediatric chronic kidney disease (CKD). While multiple eGFR equations are used clinically, their reliability in adolescents transitioning to adulthood with pediatric-onset CKD remains uncertain. This study aimed to evaluate the accuracy of 10 eGFR equations against measured GFR (mGFR) values in South Korean adolescents and young adults with CKD using data from the Korean Cohort Study for Outcomes in Patients With Pediatric Chronic Kidney Disease (KNOW-PedCKD) cohort.<br /> Methods Patients aged >= (15) years who underwent mGFR testing were included in the KNOW-PedCKD study. mGFR was determined using plasma clearance of Cr-51-EDTA or Tc-99m-DIPA. Ten eGFR equations (U25(cr), U25CysC, ( )U25(Cr-CysC ,)Schwartz(Cr) CKiD(Cr-CysC) FAS(Cr)-Age, FAS(Cr)-Ht, FAS(CysC)CKD-EPLCr, and CKD-EPICr-cysC) were compared with concurrent mGFR values. Performance was assessed using bias, precision, and accuracy expressed as the percentage of eGFR estimates within 10% [P10] and 30% [P30] of the mGFR.<br /> Results The analysis encompassed 187 mGFR measurements from 82 patients (median age 18.4 years, interquartile range (QR) 16.5-20.8; 75.9% male). Median mGFR was 42.3 (19.3-705) ml/min/1.73 m & sup2;. Overall, the U250-cyc showed the most balanced performance, with low bias (1.9ml/min/1.73 m & sup2;), high precision (SD 10.5), and accuracy values of 32.6% for P10 and 67.4% for P30. FAS(Cr)-Ht equation exhibited the highest accuracy (77.0%) and the lowest bias (-0.44), with slightly lower precision (SD 12.5). Both equations performed constantly across adolescents and young adult subgroups. In contrast, CKD-EPI equation consistently overestimated GFR with the highest bias and lowest accuracy. None of the evaluated equations achieved accuracy of 80-90% within 30% of mGFR, which are generally considered acceptable. However, after exclusion of measurements corresponding to CKD stage 5, the FAS-Ht and Schwartz(Cr) equations achieved P30 accuracies of 84.6% and 84.0%, respectively. Conclusions The eGFR equations covering children - particularly U25(Cr-CysC) and FAS(Cr)-Ht equations - provide more reliably estimates of GFR than adult equations in Korean adolescents and young adults with CKD. These findings support the use of age-spanning formulas during transitional care to improve clinical accuracy and continuity.