Cost-minimization analysis of piperacillin/tazobactam versus imipenem/cilastatin for the treatment of serious infections: a Canadian hospital perspective

• Published in: The Annals of pharmacotherapy Vol. 33; no. 2; p. 156
• Main Authors: Marra, F O, Frighetto, L O, Marra, C A, Sleigh, K M, Stiver, H G, Bryce, E A, Reynolds, R P, Jewesson, P J
• Format: Journal Article
• Language: English
• Published: United States 01.02.1999
• Subjects: Adult; Anti-Infective Agents - economics; Anti-Infective Agents - therapeutic use; Bacterial Infections - drug therapy; Bacterial Infections - economics; British Columbia; Cilastatin - economics; Cilastatin - therapeutic use; Costs and Cost Analysis; Decision Trees; Double-Blind Method; Drug Therapy, Combination; Economics, Pharmaceutical; Enzyme Inhibitors - economics; Enzyme Inhibitors - therapeutic use; Female; Humans; Imipenem - economics; Imipenem - therapeutic use; Male; Models, Economic; Penicillanic Acid - analogs & derivatives; Penicillanic Acid - economics; Penicillanic Acid - therapeutic use; Penicillins - economics; Penicillins - therapeutic use; Piperacillin - economics; Piperacillin - therapeutic use; Prospective Studies; Protease Inhibitors - economics; Protease Inhibitors - therapeutic use; Statistics, Nonparametric; Thienamycins - economics; Thienamycins - therapeutic use; Treatment Outcome; British Columbia
• ISSN: 1060-0280
• DOI: 10.1345/aph.17366

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. To describe the outcome of a pharmacoeconomic analysis of the clinical trial from the perspective of a tertiary acute-care institution. A total of 150 consenting adults originally prescribed I/C were randomly assigned to receive either P/T 4.5 g i.v. (n = 75) or I/C 500 mg i.v. (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. 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. 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.