Cost Analysis of Therapeutic Interchange of Calcium Channel Blockers for the Treatment of Hypertension: Unexpected Results from a Conversion Program

Abstract

OBJECTIVE: To examine drug expenses and overall health care resource utilization associated with a calcium channel blocker therapeutic interchange and conversion program. DESIGN: A pre/post analysis involving a retrospective cohort study design and primarily using administrative databases was done. The study was conducted from an institutional perspective using hospital-specific drug acquisition costs in 1997 dollars. SETTING: Veterans Administration Hospital, Saginaw, Michigan. PATIENTS: One hundred and one patients receiving extended-release nifedipine (Procardia XL) were converted to either amlodipine (Norvasc) or felodipine (Plendil) through the institution's conversion program. MAIN OUTCOME MEASURES: Change in total drug cost, secondary health resource utilization, study drug costs, cardiovascular drug costs, noncardiovascular drug costs, and change in severity of hypertension. RESULTS: Unexpectedly, the total cost of drug therapy was significantly higher during the nine-month postconversion period r...