The Modified CKiD Study Estimated GFR Equations for Children and Young Adults Under 25 Years of Age: Performance in a European Multicenter Cohort

The Chronic Kidney Disease in Children (CKiD) creatinine- and cystatin C-based equations have recently been modified by incorporation of continuous age- and sex-dependent k-values to yield less biased internal validation results in CKD patients under 25 years (CKiDU25)[1]. Here we report an external validation of the CKiDU25 equations in the European Kidney Function Consortium (EKFC) multicentre cohort (Table 1, Item S1)[2 3]. The cohort includes children and young adults with the vast majority having a measured GFR ≥75 mL/min/1.73m2, and thus resembles a setting where CKD is screened for.