Weighing Dosing Thresholds and EHR Integration in the Move to eGFR

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

• Rachel Khan, PharmD, associate professor of internal medicine and nephrology at the Virginia Commonwealth University School of Pharmacy;
• and Joanna Hudson, PharmD, BCPS, FASN, FCCP, professor in the departments of clinical pharmacy and translational science and medicine with an emphasis in nephrology at the University of Tennessee Health Sciences.

In the second installment of the NKF panel, the panelists explain how they handle medications whose doses change at a kidney function cutoff. Hudson focuses on safety. As estimated glomerular filtration rate (eGFR) falls to about 30 or below, she pays closer attention to drugs with a narrow therapeutic index or a risk of accumulation, such as metformin, anticoagulants, and antiarrhythmics. She adds that context matters. For example, in a patient with sepsis, underdosing a wide therapeutic index antimicrobial carries the greater risk. Khan cautions against treating thresholds as hard boundaries. Values of 28 and 31 mL/min may reflect normal daily variability, and the weight chosen for the Cockcroft-Gault equation (total, ideal, or adjusted) can shift results considerably.

Khan also highlights efficacy. Guideline-directed therapies for chronic kidney disease, including sodium-glucose cotransporter 2 inhibitors, nonsteroidal mineralocorticoid receptor antagonists, and some glucagon-like peptide-1 receptor agonists, have eGFR initiation cutoffs. Removing race from eGFR equations lowered estimates for patients who identify as Black, which may place some just below these cutoffs. When a patient falls only slightly below a threshold but would strongly benefit, for example because of significant albuminuria, she weighs risks and benefits rather than letting the number decide, and emphasizes close monitoring and follow-up. She encourages pharmacists to calculate BSA-adjusted eGFR routinely, even when it does not change the dose, so the practice becomes a habit.

On informatics, Khan describes contacting pharmacy IT, electronic health record (EHR)-specific teams, physician informatics leaders, and the clinical laboratory director at her institution to explore automatically reporting BSA-adjusted eGFR alongside creatinine clearance, an effort she has been told is feasible. Hudson has pushed for her laboratory to report an absolute eGFR value instead of the MDRD-era “greater than 60” and for eGFR to appear more prominently than the creatinine clearance shown in the Epic storyboard.

Both note practical hurdles, including rules for which height and weight to use. Hudson adds that estimating equations should not be applied in patients with unstable kidney function, such as acute kidney injury, and that cystatin C–based equations are valid options. Bzowyckyj notes that the NKF work group has issued EHR best practice recommendations and is working with EHR vendors on back-end changes.

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