#2255 Impact and interest of using the EKFC formula instead of CKD-EPI in estimating GFR in the laboratory on clinical practice

Abstract Background and Aims Early diagnosing Chronic Kidney Disease (CKD) is of major importance in daily practice, and the automatic reporting of the estimated glomerular filtration rate (eGFR) for all plasma creatinine (Pcr) determinations is mandatory. The CKD-EPI 2009 formula 1 is considered the most accurate creatinine-based GFR estimating formula in adults in Europe and is currently utilized by laboratories. However, CKD-EPI equation is inadequate in young adults 25 years and CKD-EPI equation is debated in the elderly over 75 years, with the BIS1 equation 2 showing better performance in this age group. The creatinine-based European Kidney Function Consortium (EKFC) equation 3 provides continuous GFR estimation from 2 years to adulthood and the elderly, presenting itself as a potential alternative to both the CKD-EPI and BIS1 equations. Our objective was to assess the impact of using the EKFC equation (and/or BIS1 in the elderly) compared to CKD-EPI in daily practice in identifying patients with a GFR 60 or 30 ml/min/1.73 m2, which represents the threshold for referring to a nephrologist and adjusting drug dosage, respectively. Method We retrieved data from the laboratory database, including gender, age, and the lowest measurement of Pcr for all patients over 18 years who underwent Pcr determination in November 2023. eGFR was calculated for all patients using the CKD-EPI and the EKFC equation. For patients over 70 years, eGFR was also estimated with the BIS1 equation. Pcr was assessed using an enzymatic method traceable to IDMS (Architect c®, Abbott Diagnostics). Results were expressed as the mean bias between EKFC and BIS1, and CKD-EPI (considered as the reference) according to age groups, and as the number of patients misclassified as 60 or 30 ml/min/1.73 m2. Results 10 066 patients (50.5% females, mean age 56.0 ± 21.2 years 18.0-106.7) underwent Pcr determination (mean 84.7 ± 72.3 µmol/L) with 1 706 (16.9%) and 405 (4.0%) having a GFR 60 or 30 ml/min/1.73 m2, respectively. EKFC and BIS underestimated CKD-EPI eGFR in all groups, but especially in the groups of young adults and the elderly. However, the number of misclassified patients is small, except in the elderly when CKD-EPI is considered less accurate. Conclusion The use of EKFC in laboratories to estimate eGFR offers continuous GFR estimation from 2 years to adulthood and elderly and could be an alternative to both CKD-EPI and BIS1. The automatic reporting of eGFR with EKFC by laboratories in Europe could allow for an earlier diagnosis of CKD and initiation of nephroprotection in young adults, in addition to providing better nephrological care for the elderly.