Creatinine-based estimates cannot substitute for direct glomerular filtration rate (GFR) measurements when evaluating candidates for living kidney donation, according to a new study published in Kidney International. When direct GFR measurements are not available, however, a strategy based on age-adapted GFR values estimated with either the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation or full age spectrum (FAS) equation should be preferred, investigators stated.
François Gaillard, MD, of Necker Hospital in Paris, and colleagues examined the impact of estimation versus direct measurement of pre-donation GFR on the eligibility of potential living kidney donors. It is well established that direct measurements of GFR provide the most accurate evaluation of pre-donation kidney function. Current guidelines, however, do not systematically require the use of a reference method.
In a cohort of 2733 potential kidney donors, the investigators compared the impact of 4 equations: the CKD-EPI equation, the Modification of Diet in Renal Disease (MDRD) study equation, the revised Lund-Malmö equation, and the FAS equation. The team examined the impact of using either absolute or age-adapted GFR thresholds.
The CKD-EPI equation and FAS equation had the best performance and led to the lowest proportion of improperly evaluated candidates, according to Dr Gaillard’s team. Misclassifications were more common if GFR adequacy was defined as an absolute threshold of 90 mL/ min/1.73m2 compared with an age-adapted definition (26% vs 5%).
In this cohort, interpretation of eGFR based on an absolute threshold of 90 mL/min/1.73m2 identified 1804 candidates eligible to donate. This number grew to 2648 with the use of age-adapted thresholds.
Gaillard F, Courbebaisse M, Kamar N, et al. Impact of estimation versus direct measurement of predonation glomerular filtration rate on the eligibility of potential living kidney donors. Kidney Int. 2019