Moving From Cockcroft-Gault to eGFR Introduces New Dosing Challenges in Oncology

In this National Kidney Foundation (NKF) panel, Andrew Bzowyckyj, PharmD, BCPS, CDCES, senior scientific director and learning consultant at NKF, is joined by 2 clinical pharmacists:

• Angie Maynard, PharmD, MS, BCOP, assistant professor at the Lipscomb University College of Pharmacy and Health Sciences in Nashville, Tennessee;
• and Rachel Pokorny, PharmD, BCPS, BCOP, clinical pharmacy specialist in neuro-oncology and the director of the PGY2 oncology pharmacy residency program at Vanderbilt University Medical Center in Nashville, Tennessee.

In this first segment, the 3 experts discuss the growing push to replace Cockcroft-Gault–estimated creatinine clearance with Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimated glomerular filtration rate (eGFR) for medication decisions.

The Hematology/Oncology Pharmacy Association (HOPA) and other pharmacy groups have endorsed a consensus statement calling for 1 method of assessing kidney function. The statement allows exceptions for ongoing clinical trials of narrow therapeutic index drugs. The panelists explained that the main concern is how to read survival data from landmark oncology trials that used Cockcroft-Gault, since national guidelines still refer to that equation for adult oncology dosing.

They described wide variation in how package inserts assess kidney function. Even trials from the past 5 years have used Cockcroft-Gault, older or newer CKD-EPI equations, or Modification of Diet in Renal Disease. Some pharmacists may not understand how these equations differ and may fall back on Cockcroft-Gault no matter what the label says. Most electronic health records, including Epic and Cerner, already report standardized eGFR; however, building those values into dosing order sets, drug files, and clinical decision support is a manual job that takes time, money, and informatics resources. This lift is especially heavy for safety-net and community sites, where cystatin C is often a send-out lab and results can take hours or days.

Education came up again and again as the biggest barrier. Without pharmacist awareness, order sets and decision support tools are unlikely to be updated. The panelists noted that NKF guidance supports body surface area–adjusted eGFR only in adults with stable kidney function. Patients with cancer often have CKD or develop acute kidney injury, so any order set built on eGFR would need to allow room for changes. Bzowyckyj emphasized that no equation—Cockcroft-Gault included—is valid when kidney function is changing quickly, therefore, health care professionals should continue to follow trends. He also said a wider shift will require policy changes and buy-in from oncology and nephrology stakeholders.

Learn more about the National Kidney Foundation at kidney.org and at this link.