Abstract
BACKGROUND:
In 1998 we reported the first Canadian double-blind, randomized, clinical trial involving a comparison of piperacillin/tazobactam (P/T) with imipenem/cilastatin (I/C). The present study was conducted to determine the feasibility of replacing I/C at our institution.
OBJECTIVE:
To describe the outcome of a pharmacoeconomic analysis of the clinical trial from the perspective of a tertiary acutecare institution.
METHODS:
A total of 150 consenting adults originally prescribed I/C were randomly assigned to receive either P/T 4.5 g iv (n = 75) or I/C 500 mg iv (n = 75) every six hours. Actual direct medical resources used in relation to the treatment of bacterial infections were prospectively assessed during a clinical trial; these included cost of study and ancillary antibiotics, hospitalization, diagnostic testing (radiology, laboratory assessments), and labor, as well as treatment of adverse drug reactions, antibiotic failures, and superinfections.
RESULTS:
While costs for successful treatment courses were similar across treatment arms, hospitalization costs for treatment course failures were higher for P/T recipients. Direct medical costs for treatment courses associated with a superinfection were also higher in the P/T arm. Overall costs for treatment failures with either study drug were at least twofold those observed for successful treatment courses. Mean total management cost per patient in the P/T group was $15 211 ($ CDN throughout) (95% CI $11 429 to $18 993), compared with $14 232 (95% CI $11 421 to $17 043) in the I/C group (p = 0.32), resulting in a mean cost difference of $979. Sensitivity analyses revealed that the superiority of I/C over P/T for successful treatment of serious infections was sensitive to changes in the cost of hospitalization and drug efficacy for either drug.
CONCLUSIONS:
Based on the results of the clinical trial, P/T and I/C offer similar clinical, microbiologic, and toxicity outcomes in hospitalized patients with serious infections. Under base–case conditions, our pharmacoeconomic analysis showed that I/C was a cost-effective alternative to P/T at the dosage regimens studied. However, this finding was sensitive to plausible changes in both clinical and economic parameters.
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