24 Jun Choice of Kidney Function Equation Important In Risk Evaluation Prior To Stent Surgery

MedicalResearch.com Interview with:
Jessica Parsh MD
Hitinder Gurm MBBS
Department of Internal Medicineb
University of Michigan Health System

Medical Research: What is the background for this study? What are the main findings?

Response: Chronic kidney disease (CKD) is associated with adverse events after percutaneous coronary interventions (PCI). Estimated glomerular filtration rate (eGFR) is used for CKD stage classification and there are several widely used eGFR equations, including the Cockcroft-Gault, CKD-EPI, and MDRD. Others have shown that the CKD-EPI equation is more accurate, more precise and less bias. The current Kidney Disease Improving Global Outcomes (KDIGO) guidelines recommend the use of CKD-EPI. Even so, there remains wide variability among equation choice between different institutions as well as between different health care providers (physicians, pharmacists, etc). In addition, in a recent survey, up to 12% of providers were “unsure” of which equation they used. Furthermore, the FDA has no clear guidelines regarding equation selection for pharmacokinetic studies of novel medications and the equation used for development of a particular drug is not always clearly labeled on package inserts.

Using data from the Blue Cross Blue Shield of Michigan Cardiovascular Consortium for almost 130,000 patients who underwent PCI, we investigated whether use of different eGFR equations would lead to discrepant eGFR output, how this would lead to CKD stage reclassification and whether CKD stage reclassification by a certain equation led to improved risk prognostication for adverse events. We also studied how calculation of eGFR by various equations would affect drug dosing recommendations for common renally-dosed antiplatelet and antithrombotic medications. We found that there was wide discrepancy among the eGFR output of the various equations and this led to significant CKD stage reclassification (with agreement on stage classification as low as 56% for CKD-EPI and Cockcroft-Gault). Further, our data from receiver operating characteristic analysis and net reclassification index analysis support CKD-EPI as superior for risk prognostication for renal adverse outcomes of acute kidney injury and new requirement for dialysis. In regards to drug dosing, agreement between all three equations on dosing adjustment was as low as 34% (bivalirudin with eGFR cutoff < 30 ml/min/1.73²).

Medical Research: What should clinicians and patients take away from your report?

Response: Our study demonstrates that eGFR equation selection is important since the various equations lead to very discrepant eGFR values and CKD stage classification. Further, for renal adverse outcomes of acute kidney injury and new requirement for dialysis, the use of CKD-EPI leads to improved risk prognostication. These findings compliment many other studies which have demonstrated the superiority of the CKD-EPI equation in terms of accuracy, precision and bias. Therefore, our study supports increased awareness of equation selection by providers and the use of CKD-EPI for risk stratification for patients undergoing PCI.

Given the potential for harm with inappropriate drug dosing in patients with CKD, our findings that various eGFR equations lead to large discrepancies in drug dosing recommendations is concerning. When possible, providers should review package labeling and dose medications using the same eGFR equation used in the original pharmacokinetic design.

Medical Research: What recommendations do you have for future research as a result of this study?

Response: Future research investigating the potential harm related to inaccurate drug dosing secondary to inappropriate eGFR equation selection is needed. From there, investigations into whether pursuing a standardized eGFR equation selection approach for new drug pharmacokinetic design would lead to a decrease in harm from drug dosing inaccuracies will be an important next step to improve the safety of patients living with CKD.

Citation:

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Jessica Parsh MD, Hitinder Gurm MBBS, Department of Internal Medicineb,  University of Michigan Health System (2015). Choice of Kidney Function Equation Important In Risk Evaluation Prior To Stent Surgery 

Last Updated on June 24, 2015 by Marie Benz MD FAAD