Pharmacy professor promotes kidney assessment that provides accurate, equitable care

BUFFALO, N.Y. — For decades, pharmacists and medical institutions have relied on the Cockcroft-Gault (C-G) estimated creatinine clearance assessment to determine medication dosing and treatment for patients with chronic kidney disease, a condition that affects 1 in 7 adults in the United States.

The 50-year-old assessment, which was based upon a small group of white men using older lab modules, has multiple problems, notes Calvin Meaney, PharmD, clinical associate professor of pharmacy practice who specializes in nephrology at the University at Buffalo School of Pharmacy and Pharmaceutical Sciences.

Namely, it can overestimate how the kidneys work and is used inconsistently by clinicians.

The Food and Drug Administration (FDA) recommended the test early on to determine dosing for kidney disease patients, which included questions on age, sex, body weight, and serum creatinine (a blood test). It’s still being used by more than 60% of hospital pharmacists today, says Meaney, who also has a clinical practice at the Erie County Medical Center, which no longer uses this test.

A newer assessment, the estimated glomerular filtration rate (eGFR), developed in 1999, was more accurate but had another problem. It used age, sex and race in its calculations for staging of the disease, which led to racial disparities in access to kidney transplants.

Meaney recently co-authored a commentary promoting the 2021 version of the eGFR, which removes race from the equation. It was recently published in the Journal of the American College of Clinical Pharmacy, with contributions from several pharmacy researchers who are all members of the Nephrology Practice and Research Network.

“It’s a topic that’s well known in the nephrology community, but it’s not as well known by pharmacists or other providers outside of nephrology,” Meaney says. “However, it affects everyone because all pharmacists dose medications according to a patient’s kidney function, among other factors. Having an accurate and precise measurement of kidney function is really important to dose medications, even if you’re working in cardiology or oncology.”

The eGFR equation was derived from thousands of patients across the spectrum of kidney diseases representing multiple ethnicities and disease states, Meaney says. It’s much more accurate and more precise than the C-G assessment.

“Pharmacists play a crucial role in dosing medications for patients with kidney dysfunction, often collaborating with physicians to adjust dosages based on eGFR values,” he says. “We want them to be informed of what we see as best practices.”

He explains having accurate and precise information is crucial as dosing too high can lead to toxicity while dosing too low can be ineffective.

“It also lets pharmacists know whether or not a patient should receive a specific drug,” he adds. “The decision-making pathways are more complex than just dosage.”

In the initial development of the eGFR equation, the African American race was incorporated as a factor in addition to sex and age.

“What we came to learn was that when you use the race factor, it actually changes where people show up on the transplant eligibility list,” Meaney says. “It led to a lot of disparities in access to a kidney transplant, which is the gold standard treatment if a patient progresses to kidney failure. That was the impetus for this race-free approach.”

Along with removing race from the equation, the 2021 version of the eGFR has been shown to be more precise and accurate at staging diseases across a variety of ethnicities.

In 2024, the FDA shifts its recommendation to the newer eGFR equation, though not all hospitals or pharmacists have followed suit.

Overall, the paper’s recommendation to pharmacists is simple: use the most accurate and fair methods available to choose medication doses, especially for patients with kidney disease.

“The outdated tests are still very pervasive, especially in the pharmacy community,” Meaney says. “I think they are holding onto something from the past because it’s what they’re accustomed to.”