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Cost-effectiveness of abbreviating the duration of intravenous antibacterial therapy with oral fluoroquinolones |
Jensen K M, Paladino J A |
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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. Health technology Administration of oral antibacterials (ciprofloxacin or enoxacin), as early switch therapy to abbreviate intravenous (IV) antibacterial therapy.
Economic study type Cost-effectiveness analysis.
Study population Hospitalized adult patients with serious bacterial infections, caused by organisms that were susceptible to the parenteral antibacterials and the oral fluoroquinolones. Patients' age ranged from 19 to 98 with a mean age of 65 years.50% of patients were males.
Setting Hospital. Both the clinical trials and economic study were carried out in Buffalo, USA.
Dates to which data relate Effectiveness data were based on clinical trials reported during 1990/1991. Costs were reported in 1995 prices.
Source of effectiveness data Efficacy estimates were obtained from a review/synthesis of previous studies.
Link between effectiveness and cost data Cost data were collected retrospectively from the charts of the same patient sample as participated in the trials.
Study sample A total of 205 patients were initially enrolled in the 2 trials. No power calculations were reported. 187 patients who had complete records were included in the cost-effectiveness study of whom 106 were placed in the switch therapy group and 81 in the standard IV therapy group.
Study design Randomized controlled trial. The length of follow-up was not reported. 18 (9%) participants were excluded from the economic study due to incomplete hospital records. The assessor of patients' outcomes was blinded to treatment assignment.
Analysis of effectiveness Analysis of clinical efficacy was based on intention-to-treat. Outcomes of"success", "failure", and "indeterminate outcome" were assessed on the basis of clinical improvement. Success was if the antibacterial therapy was no longer needed, failure was if additional antibacterial therapy was needed or an adverse drug reaction occurred, and indeterminate if no evaluation was possible. Baseline characteristics were shown to be comparable, the only statistically significant difference was in bodyweight.
Effectiveness results The probability of success was 0.76 for the switch therapy group and 0.72 for the standard IV therapy group, a nonsignificant difference (p=0.7). The probability of failure was 0.19 and 0.21, respectively (p=0.7). The probability of failure due to lack of efficacy was 0.08 in the switch therapy group and 0.20 in the standard IV therapy group (p=0.03), and due to adverse drug reaction 0.11 and 0.01, respectively (p=0.02). Adverse events which were probably related to a study drug occurred in 50% of switch therapy patients and in 33% of standard IV therapy patients (p=0.02).
Clinical conclusions No difference in efficacy was found.
Modelling Modelling was by decision tree incorporating efficacy and cost outcomes of alternative regimens.
Measure of benefits used in the economic analysis Successful cases. Quality of life was not assessed.
Direct costs No discounting was applied, since benefits occurred at the same time as costs. Quantities and costs were not reported separately. Costs included treatment cost during the initial hospitalization period, and during the follow up after the patient was discharged. Quantities for costing were obtained from retrospective analysis of patient charts. Unit costs for preparation and administration of IV and oral doses were based on earlier studies and converted to 1995 US dollars by applying a 5% increase per year. Other cost items were valued using a standard Medicare fee schedule for 1995. Protocol-driven costs were excluded from the analysis. The perspective of an Integrated Healthcare Network (IHN) was adopted in costing, defined as wider scope of both inpatient and outpatient care costs. However, the actual costs boundary was that of the hospital.
Statistical analysis of costs The cost difference between study groups was assessed using Wilcoxon Rank Sum Test, 2-tailed, p<0.05 considered as statistically significant.
Sensitivity analysis A one-way-sensitivity analysis was carried out by varying the probability of the treatments' success, the cost per day of hospitalisation, and drug cost.
Estimated benefits used in the economic analysis No difference in success rates was found. Side-effects were considered only in terms of cost outcomes.
Cost results Mean (level 4) cost per patient was $4,818 (standard error of the mean: $269) for switch therapy and $5,028 ($294) for standard IV therapy group. Wilcoxon Rank Sum Test indicated a nonsignificant difference between the two groups (p=0.14). No discounting was applied. Costs of treating adverse effects were included.
Synthesis of costs and benefits The paper reported cost per successful outcome for the base case. Cost per successful outcome was $6,339 for switch therapy and $6,983 for standard IV therapy. No incremental analysis was performed. The mean cost savings (level 4) of switch therapy was $210 per patient. Sensitivity analysis demonstrated that cost savings would vanish if the efficacy of switch therapy decreased by 6 to 70% and the efficacy of standard IV therapy increased by 8 to 80%, simultaneously.
Authors' conclusions Clinical success rates were similar for the 2 groups. Switch therapy was a cost effective treatment with no demonstrated change in efficacy compared with standard IV therapy.
CRD COMMENTARY - Selection of comparators A justification was given for the comparator used. The comparator chosen, which was a commonly used regimen for treatment of serious infections in hospital, was a parenteral antibacterial therapy for 7 to 8 days, with consequent change to oral antibacterials when needed.
Validity of estimate of measure of benefit The study was based on the combined results of 2 randomized controlled trials, which seem to have been properly undertaken.
Validity of estimate of costs Adequate detail was given of the cost items included, prices, and price dates. However, the quantities of resources used in addition to the length of stay in hospital would have been of interest.
Other issues The conclusion that switch therapy is more cost-effective warrants some caution, since neither the efficacy nor the mean costs were statically significantly between the two groups. The unit costs were based on a Medicare fee schedule and may not be generalisable in other systems or countries. It should be noted that the larger proportion (50% vs 33%) of patients with adverse events in the switch therapy group may make a difference in terms of its impact on patients' quality of life which was not assessed in this study. Also, more discussion about the 3 patients who died should have been provided, at least their distribution between switch therapy and standard IV therapy groups.
Bibliographic details Jensen K M, Paladino J A. Cost-effectiveness of abbreviating the duration of intravenous antibacterial therapy with oral fluoroquinolones. PharmacoEconomics 1997; 11(1): 64-74 Indexing Status Subject indexing assigned by NLM MeSH Adult; Aged; Ciprofloxacin /administration & Cost-Benefit Analysis /economics; Enoxacin /administration & Female; Humans; Injections, Intravenous /economics; Male; Middle Aged; dosage /economics; dosage /economics AccessionNumber 21997008038 Date bibliographic record published 30/09/1998 Date abstract record published 30/09/1998 |
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