Does Routine EGFR Reporting Adversely Affect Medication Dosing in the Elderly?

Abstract

Aim: To identify if drug dosing errors occur in patients age ≥ 65 based on usual reporting of estimated glomerular filtration rate (eGFR) com pared with reporting by the Cockcroft-Gault (CG) equation. practice Background: Creatinine-based GFR equations are commonly used in clinical to guide drug dosing. The Australian Therapeutic Guidelines recommend use of the CG derived eGFR as the basis for drug dosing guidelines (Therapeutic Guidelines, 2019. Estimating glomerular filtration rate in adults). However, the standard reporting of eGFR within Australian hospitals and laboratories is via the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI 2021) equation. Methods: We studied a single-centre prospective cohort of aged care patients, age ≥ 65-years-old, admitted under the Geriatrics Team at Port Macquarie Base Hospital, Australia, over 3 months. 163 patients were included, with 8 excluded as weights were not recorded in the year prior. Creatinine was calculated on admission and in the 48 hours prior to discharge and the average of these two results used to calcu late eGFR using CG and CKD-EPI 2021. Results: Of the 208 medications prescribed that required adjustment based on renal function, there were 38 (18%) dosing errors. The most commondrugs in question were perindopril, apixaban and ciprofloxacin. Twenty-nine (76%) of these errors occurred regardless of which eGFR calculation was used. The other nine (24%) dosing errors (7 over-dosed and 2 under-dosed) occurred if using CKD-EPI 2021 rather than CG. Conclusions: Minimal differences occur in drug dosing when using CG and CKD-EPI 2021 formulas. However, when discrepancies occur, use of CKD-EPI 2021 typically results in medication overdoses, which could result in adverse reactions in an at-risk population.