The Impact of eGFR Equation Selection | Journal Scan

Study Questions:

What is the impact of the use of different estimated glomerular filtration rate (eGFR) equations on different chronic kidney disease (CKD) staging of patients undergoing percutaneous coronary intervention (PCI), and how does reclassification correlate with risk of adverse events after PCI?


This was a retrospective post-hoc analysis using data from the Blue Cross Blue Shield of Michigan Cardiovascular Consortium, a regional registry of all patients undergoing PCI at nonfederal hospitals in Michigan. eGFR was calculated using the Cockcroft-Gault, Modification of Diet in Renal Disease Study (MDRD), and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations for 128,805 patients undergoing PCI in the state of Michigan. Agreement between patient pre-PCI eGFR estimates and resultant CKD stage classifications, their ability to discriminate post-procedural in-hospital clinical outcomes, and the impact of equation choice on dosing recommendations for commonly used antiplatelet and antithrombotic medications were investigated.


CKD-EPI best discriminated post-PCI mortality by receiver operator characteristic analysis. There was wide variability in eGFR, which persisted after grouping by CKD stages. Reclassification by CKD-EPI resulted in net reclassification index improvement for acute kidney injury and new requirement for dialysis. Equation choice affected drug-dosing recommendations with the formulae agreeing for only 50.3%, 40.0%, and 34.3% of potentially impacted patients for eGFR cutoffs of <60, <50, and <30 ml/min/1.732, respectively.


The authors concluded that different eGFR equations result in CKD stage reclassification that has major clinical implications for predicting adverse outcomes after PCI.


This analysis suggests that there is wide variation in the estimation of GFR among the main equations used today, which may lead to CKD stage reclassification in a large proportion of patients and can carry important implications regarding the risk for major PCI adverse outcomes. Furthermore, calculation of eGFR by the various equations results in large discrepancies in drug-dosing recommendations for commonly used antiplatelet and antithrombotic agents. Additional prospective studies are needed to determine the optimum method for estimation of renal clearance of drugs used in patients with CKD undergoing cardiovascular procedures.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention

Keywords: Acute Kidney Injury, Fibrinolytic Agents, Glomerular Filtration Rate, Kidney Diseases, Percutaneous Coronary Intervention, Prospective Studies, Registries, Renal Dialysis, Renal Insufficiency, Chronic, Retrospective Studies

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