A Systematic Review of Renal Function Estimation Equations

Abstract

This review summarizes the development of various renal function estimation equations and their use in the clinical and drug development space today. We provide a review of recent literature published regarding their concordance and accuracy as compared to measured renal function by way of creatinine clearance (CrCl) or glomerular filtration rate (GFR) in staging chronic kidney disease (CKD) and dose adjusting renally eliminated drugs. The choice of specific renal function estimation equations has been a topic of much debate. While clinical guidelines are continuously updated, product labels contain potentially different recommendations. Overall, Chronic Kidney Disease Epidemiology (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) are found to have higher concordance with one another than either equation with Cockcroft-Gault (CG). Although many studies assessing the accuracy of estimation equations found CKD-EPI to be closest to measured GFR, most labs are still reporting CG and MDRD as an assessment of renal function. Each of these equations have been developed in different patient populations and include different variables which makes it critical to understand and address potential discrepancies when using them to stage patients with CKD or dose adjust renally eliminated drugs. An understanding of the development and accuracy of renal function estimation equations is required to use them appropriately in clinic. As clinical and drug development guidelines continue to be updated and new products are undergoing development, further study is required to come to some agreement regarding the use of these equations in both environments.