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| Pharmacoeconomics of ciprofloxacin plus metronidazole vs. piperacillin-tazobactam for complicated intra-abdominal infections |
| Paladino J A, Gilliland-Johnson K K, Adelman M H, Cohn S M |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. CRD summary The study compared the cost-effectiveness of two antibiotic regimens, ciprofloxacin-metronidazole versus piperacillin-tazobactam, for the treatment of adult patients with complicated intra-abdominal infections requiring surgical intervention or percutaneous drainage. The ciprofloxacin-metronidazole regimen improved the success rate without increasing hospital costs. On the whole, the methodology of the study seemed appropriate and was presented clearly. The authors’ conclusions appear appropriate despite the limited sensitivity analysis around key model inputs. Type of economic evaluation Cost-effectiveness analysis Study objective The objective was to compare the cost-effectiveness of two antibiotic regimens, ciprofloxacin-metronidazole versus piperacillin-tazobactam, for the treatment of adult patients with complicated intra-abdominal infections requiring surgical intervention or percutaneous drainage. Interventions The two regimens under examination were ciprofloxacin 400 mg intravenously (IV) every 12 hours plus metronidazole 500 mg IV every 6 hours versus piperacillin-tazobactam 3.375 g IV every 6 hours. Conversion to oral antibiotics was allowed after 48 hours if the patients had improved clinically. Methods Analytical approach:This economic evaluation was based on a single study, the data from which were used to populate a decision tree. The time horizon of the analysis was restricted to the in-hospital stay. The authors stated that the perspective of the hospital was adopted in the study.
Effectiveness data:The clinical data came from a multi-centre (34 medical institutions), blinded, randomised clinical trial (RCT), in which patients were treated for a maximum of 14 days and further followed for a maximum of 5 weeks post-therapy. Of the 459 patients included in the intention to treat analysis, 244 (131 in the ciprofloxacin-metronidazole group and 113 in the piperacillin-tazobactam group) were included in this economic evaluation. The two groups were similar in terms of their demographic and clinical characteristics. Sub-group analyses were performed for patients with or without appendicitis and for those able or unable to receive oral antibiotics. The key clinical outcome was the success rate with consequent switch to oral antibiotics.
Monetary benefit and utility valuations:None.
Measure of benefit:The summary benefit measure was the success rate. This was estimated directly from the RCT.
Cost data:The costs considered were for study antibiotics, other antimicrobials, preparation and administration of study drugs, treatment of adverse events, laboratory tests, diagnostic and radiological procedures, therapeutic adjuncts and procedures, operative or percutaneous procedures, and hospital stay. Resource use was derived from the sample of 244 patients enrolled in the RCT. Most of the costs came from two reference hospitals in Buffalo, New York. The cost of hospital stay was obtained from the American Hospital Association. The costs were in US dollars ($). The price year was 2001.
Analysis of uncertainty:A deterministic sensitivity analysis was undertaken to address the issue of uncertainty. Both clinical and economic inputs of the model were varied. The authors appear to have defined the alternative estimates. The authors attempted to perform an alternative analysis for the Canadian setting, but this was not possible given the small number of Canadian patients. Results Treatment success rate and consequent switch to oral antibiotics was 75% with ciprofloxacin-metronidazole and 65% with piperacillin-tazobactam.
The total costs per patient were $10,662 (± 7,793) with ciprofloxacin-metronidazole and $10,009 (± 7,023) with piperacillin-tazobactam, (p=0.492).
Patients with appendicitis had significantly lower costs than those without appendicitis. When adjusting costs for the different proportion of patients with appendicitis, the expected costs were $10,518 with ciprofloxacin-metronidazole and $10,181 with piperacillin-tazobactam.
The average cost per expected success was $14,216 with ciprofloxacin-metronidazole and $15,398 with piperacillin-tazobactam. This resulted in an incremental cost per additional successfully treated patient of $6,530 with ciprofloxacin-metronidazole over piperacillin-tazobactam.
The sub-group analysis showed that the costs were lower in patients able to switch to oral antibiotics and in those with appendicitis. Variations in costs showed that IV regimens were far more expensive than IV-oral switch therapies. A threshold analysis showed that the success rate for piperacillin-tazobactam would have to increase by 8.8%, or that for ciprofloxacin-metronidazole would have to decrease by 7.25%, to make piperacillin-tazobactam the most cost-effective option. Authors' conclusions The authors concluded that the use of ciprofloxacin-metronidazole for the treatment of complicated intra-abdominal infections was more effective than piperacillin-tazobactam without increasing hospital costs. CRD commentary Interventions:The authors did not provide an explicit justification for their selection of the comparators, but they are likely to reflect two commonly used antibiotic therapies.
Effectiveness/benefits:The clinical estimates came from an RCT, which is usually considered to be a valid source of clinical data. The randomised, multi-centre and blinded design should have ensured the validity of the effectiveness data. The authors reported reasons for excluding patients from the economic analysis. The baseline comparability of the study groups and the sub-group analyses further enhanced the internal validity of the clinical study. The benefit measure, which was derived directly from the RCT, represents an intermediate impact of the treatments on patient health and may be difficult to compare with the benefits of other health care interventions.
Costs:The analysis of the costs was consistent with the authors' stated perspective. However, the unit costs and the resource quantities were not presented separately; the costs were presented as macro-categories. The sources used to derive the costs were reported, as were other details of the analysis such as the price year and the alternative sources used in the sensitivity analysis. Resource use reflected the actual consumption of health services for patients in the RCT.
Analysis and results:The synthesis of the costs and benefits was appropriately performed. The results of the base-case analysis were presented clearly, and the findings from the sensitivity analyses were discussed. The issue of uncertainty was only partially addressed as the sensitivity analysis focused on specific model inputs, especially economic data. The authors acknowledged that the clinical study was performed some years before the economic analysis, when resistance to fluoroquinolones was lower than in the following years. More recent analyses might be more favourable to piperacillin-tazobactam, given the marked increase in resistance to fluoroquinolones.
Concluding remarks:The analysis was, in general, well conducted, although the issue of uncertainty was not extensively addressed. Overall, the authors’ conclusions appear valid. Bibliographic details Paladino J A, Gilliland-Johnson K K, Adelman M H, Cohn S M. Pharmacoeconomics of ciprofloxacin plus metronidazole vs. piperacillin-tazobactam for complicated intra-abdominal infections. Surgical Infections 2008; 9(3): 325-333 Other publications of related interest Cohn SM, Lipsett PA, Buchman TG, et al. Comparison of intravenous/oral ciprofloxacin plus metronidazole versus piperacillin-tazobactam in the treatment of complicated intraabdominal infections. Ann Surg 2000;232:254-62.
Welters DJ, Solomkin JS, Paladino JA. Cost-effectiveness of ciprofloxacin plus metronidazole versus imipenem-cilastatin in the treatment of intraabdominal infections. Pharmacoeconomics 1999;16:551-61.
Barie PS, Gill MA, Yellin AE, et al. Pharmacoeconomics of poperacillin-tazobactam and imiprenem/cilastatin in the treatment of complicated intraabdominal infection. Surg Infect 2004;5:269-80. Indexing Status Subject indexing assigned by NLM MeSH Abdominal Abscess /complications /drug therapy /microbiology; Adult; Aged; Anti-Bacterial Agents /administration & Appendicitis /complications /drug therapy /microbiology; Ciprofloxacin /administration & Cost-Benefit Analysis; Double-Blind Method; Drug Therapy, Combination; Economics, Pharmaceutical; Female; Humans; Male; Metronidazole /administration & Middle Aged; Penicillanic Acid /administration & Peritonitis /complications /drug therapy /microbiology; Piperacillin /administration & Treatment Outcome; derivatives /economics /therapeutic use; dosage /analogs & dosage /economics /therapeutic use; dosage /economics /therapeutic use; dosage /economics /therapeutic use; dosage /economics /therapeutic use AccessionNumber 22008101468 Date bibliographic record published 01/12/2008 Date abstract record published 23/12/2008 |
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