Discrepancy Between Equations Estimating Kidney Function in Geriatric Care: A Study of Implications for Drug...

In older patients, the agreement is low between creatinine clearance estimated with the Cockcroft-Gault equation (eCrCl) and glomerular filtration rate estimated with the Chronic Kidney Disease Epidemiology Collaboration equation (eGFR_CKD-EPI). The implications of these discrepancies for drug prescription have so far been assessed only for a few selected molecules.

The aim of this study was to investigate the proportion of geriatric patients receiving drugs with a different recommended dose or indication (i.e. an adjustment discrepancy) depending on eCrCl versus eGFR_CKD-EPI estimates of kidney function.

Patients admitted to acute geriatric care units in our university hospital were eligible for inclusion. All drug classes were studied. We retrospectively determined recommended prescriptions according to eCrCl and eGFR_CKD-EPI.

Sixty percent of patients received at least one drug requiring dose adjustment and/or received a drug with a relative contraindication based on their estimated kidney function. Thirty-one percent of patients received at least one drug with an adjustment discrepancy: 20% received at least one drug for which the recommended dose differed depending on eCrCl versus eGFR_CKD-EPI estimates of kidney function, 4% received a drug with a relative contraindication according to eCrCl but not eGFR_CKD-EPI, and 7% received both. Factors independently associated with an adjustment discrepancy were older age and lower weight. Main drug classes involved were benzodiazepines, anticoagulants, and anti-microbial drugs.

In acute geriatric care units, recommended drug dose adjustments are frequently discordant according to the equations used to estimate kidney function, notably for benzodiazepines, anticoagulants, and anti-microbial drugs. The consequences for treatment efficacy and safety should be investigated.