Potentially inappropriate prescribing of primarily renally cleared medications for older veterans affairs nursing home patients

Abstract

Background: Inappropriate prescribing of primarily renally cleared medications in older patients with kidney disease can lead to adverse outcomes.

Objectives: To estimate the prevalence of potentially inappropriate prescribing of 21 primarily renally cleared medications based on 2 separate estimates of renal function and to identify factors associated with this form of suboptimal prescribing in older VA nursing home (NH) patients.

Design: Longitudinal study

Participants: Participants were 1304 patients, aged 65 years or older, admitted between January 1, 2004, and June 30, 2005, for 90 days or more to 1 of 133 VA NHs.

Main measures: Potentially inappropriate prescribing of primarily renally cleared medications determined by estimating creatinine clearance using the Cockcroft Gault (CG) and Modification of Diet in Renal Disease (MDRD) equations and applying explicit guidelines for contraindicated medications and dosing.

Key results: The median estimated creatinine clearance via CG was 67 mL/min, whereas it was 80 mL/min/1.73m(2) with the MDRD. Overall, 11.89% patients via CG and only 5.98% via MDRD had evidence of potentially inappropriate prescribing of at least 1 renally cleared medication. The most commonly involved medications were ranitidine, glyburide, gabapentin, and nitrofurantoin. Factors associated with potentially inappropriate prescribing as per the CG were age older than 85 (adjusted odds ratio [AOR] 4.24, 95% confidence interval [CI] 2.42-7.43), obesity (AOR 0.26, 95% CI 0.14-0.50) and having multiple comorbidities (AOR 1.09 for each unit increase in the Charlson comorbidity index, 95% CI 1.01-1.19).

Conclusions: Potentially inappropriate prescribing of renally cleared medications is common in older VA NH patients. Intervention studies to improve the prescribing of primarily renally cleared medications in nursing homes are needed.