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Economic evaluation of ciprofloxacin compared with usual antibacterial care for the treatment of acute exacerbations of chronic bronchitis in patients followed for 1 year |
Torrance G, Walker V, Grossman R, Mukherjee J, Vaughan D, La Forge J, Lampron N |
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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 Use of ciprofloxacin for the treatment of acute exacerbations of chronic bronchitis (AECB) compared to usual antibacterial care.
Economic study type Cost-effectiveness analysis, cost-utility analysis and cost-benefit analysis.
Study population An adult outpatient aged 18 or over with chronic bronchitis that presented with type I or type II AECB.
Setting The clinical study took place in the secondary care sector. The economic study was conducted in Ontario, Canada.
Dates to which data relate Effectiveness data were collected between November 1993 and June 1994. Prices related to 1994/1995.
Source of effectiveness data The estimate for final outcomes was based on a single study.
Link between effectiveness and cost data Costing was undertaken prospectively on the same patient sample as that used in the effectiveness analysis.
Study sample There were no significant differences between the treatment groups in terms of demographic characteristics and chronic bronchitis history, except that there were more women in the ciprofloxacin group. 240 AECB patients were enrolled and 120 were assigned to each group. No power calculations to determine sample size were described.
Study design This was an unblinded multi-centre, prospective, randomised controlled trial. Study participants were followed up for one year. Five patients receiving ciprofloxacin and 13 receiving usual care were not included in the study (reasons were provided). A further 10 patients in the ciprofloxacin and 11 in the usual care group did not complete the study. Two patients in each group died and the others were lost to follow-up or noncompliant.
Analysis of effectiveness All analyses were performed on an intention to treat basis. The main health outcome used in the effectiveness analysis was the number of AECB-symptom days averted. Also the Health Utilities Index (HUI) was used to measure patients' health-related quality of life (HR-QoL) throughout the study. At analysis, groups were shown to be comparable in demographic characteristics, though there were more women than men in the ciprofloxacin group.
Effectiveness results The mean annual AECB-symptom days per patient were 42.86 for the ciprofloxacin group (SD=30.36) and 45.62 (SD=30.96) for the usual care group: a reduction of 2.76 AECB-symptom days. The 95% confidence interval (CI) for the difference in mean AECB-symptom days per patient per year (usual care - ciprofloxacin) was -5.31 to 10.83 days. The mean HUI during the first AECB was 0.72 (SD=0.20) and 0.68 (SD=0.19) for ciprofloxacin and usual care respectively. The mean utility during the remaining AECB was 0.74 (SD=0.18) and 0.69 (SD=0.22) for the ciprofloxacin and usual care groups respectively.
Clinical conclusions The broad activity of ciprofloxacin shortens the duration of AECB and reduces the AECB-symptom days per patient per year compared to other antibacterials.
Measure of benefits used in the economic analysis For the cost-effectiveness analysis, mean annual AECB-symptom days per patient were calculated. For the cost-utility analysis, utilities were generated using the Health Utilities Index (HUI) and quality-adjusted life years (QALYs) gained were calculated. St. George's Respiratory Questionnaire, the Nottingham Health Profile and the HUI were used at the end of each AECB and every 3 months. For the cost-benefit analysis, in order to express benefits in monetary terms, patients also completed a self-administered willingness to pay (WTP) questionnaire following each AECB, asking them the maximum amount they would have been willing to pay to have avoided that particular exacerbation and all the problems associated with them. WTP data did not pass scope tests for reasonableness.
Direct costs The following types of resource utilisation were collected: antibacterials for the AECB, concomitant medications (such as oxygen, bronchodilators and antihistamines), outpatient resources (such as healthcare assessments, diagnostic tests and procedures), emergency room visits, and hospitalisations. Because of the time horizon (1 year) costs were not discounted. 1994/1995 prices were used, obtained from Ontario or Quebec sources, depending on the province in which the patient resided, with the exception of hospital-based costs for which Ontario costs were employed. The quantity/cost boundary adopted was the societal perspective and the main third-party payer (Ministry of Health). Quantity and cost estimations were based on actual data.
Statistical analysis of costs Statistical analysis was performed based on an estimation approach. Costs were not treated in a stochastic way.
Indirect Costs Patient and caregiver out-of-pocket expenses such as baby-sitting, travel and patient/caregiver time lost or cut down from work or from usual major activity were considered. The average Canadian industrial aggregate weekly wage rate of Can$566 was used to calculate time loss or cut down from work or usual major activity for patients and their caregivers. Quantity and cost information was based on actual data.
Currency Canadian dollars (Can$) (1995 exchange rate US$1 = Can$1.3587)
Sensitivity analysis To test the robustness of the results, sensitivity analyses were performed on key variables to observe:
(1) the upper and lower values of the 95% CI for the mean difference in consequences between groups were employed for each of the CEA, CUA and CBA; and
(2) the median annual willingness to pay for the CBA.
One-way simple sensitivity analyses and threshold analyses were undertaken.
Estimated benefits used in the economic analysis For the base-case analysis, from the societal perspective, the QALYs gained were 0.031 per patient per year for the ciprofloxacin patients above the usual care group (an increase in the annual QALYs from 0.76 to 0.79). The mean WTP was Can$367 greater in the ciprofloxacin group compared to the usual care group.
Cost results The incremental annual cost was Can$578 greater in the ciprofloxacin group compared to the usual care group from the societal viewpoint (95% CI difference in means of the ciprofloxacin group compared to the usual care group was -Can$778 to Can$132). From the perspective of the Ministry of Health, the mean total cost was Can$840 greater in the ciprofloxacin group (95% CI difference in means: -Can$445 to Can$2125). For the formulary, the mean total cost per patient was Can$71 less in the ciprofloxacin group (95% CI difference in means: -Can$290 to Can$148).
Synthesis of costs and benefits For cost-effectiveness analysis the ratio per AECB-symptom day averted was Can$209 from the societal viewpoint and Can$304 from the third-party payer perspective. The cost-utility analysis ratio was Can$18,588 per QALY gained (societal) and Can$27,025per QALY gained (Ministry of health). According to Laupacis criteria, these cost-utility analysis results are strong evidence in favour of adopting the drug from the societal viewpoint and moderate evidence in favour from the viewpoint of the third-party payer. A subgroup analysis performed by the authors suggested that ciprofloxacin may be particularly cost-effective, even win-win, in patients with more severe disease. For the cost-benefit analysis the net benefit of ciprofloxacin over usual care was -Can$945 from the societal perspective (95% CI for a net benefit: -$Can2,323 to Can$433).
Authors' conclusions The use of ciprofloxacin was more costly and resulted in better outcomes compared to usual bacterial care. The sensitivity analyses conducted indicated that results are quite robust. However, the uncertainty associated with the results shows that the findings cannot be accepted without question.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparators (ciprofloxacin versus usual antibacterial care) for the treatment of AECB is clear.
Validity of estimate of measure of benefit The authors used the HUI to obtain QALYs and this is a valid way to ascertain benefits. An open-ended, self-administered WTP questionnaire was used to generate benefits for use in the cost-benefit analysis. The WTP question used was specific to the study and its use has not been validated. The authors argued that the WTP data did not pass scope tests for reasonableness.
Validity of estimate of costs The cost analysis was complete and thorough, with no important elements missing. The use of the societal perspective for cost analysis, and the inclusion of the patient and caregiver costs, was well done.
Other issues In general this was a very well conducted study. However, there are a few issues that could have been addressed more closely such as the generalisability of results to other settings or countries. Also, the authors stated that 15% of AECB episodes were not recorded during the follow-up, as patients did not report them. The inclusion of these omitted episodes in the final analysis may lead to significant changes in the final results.
Implications of the study A further study with a larger sample size would be useful to confirm (or deny) the findings of this study.
Source of funding Funding from Bayer Inc, Canada.
Bibliographic details Torrance G, Walker V, Grossman R, Mukherjee J, Vaughan D, La Forge J, Lampron N. Economic evaluation of ciprofloxacin compared with usual antibacterial care for the treatment of acute exacerbations of chronic bronchitis in patients followed for 1 year. PharmacoEconomics 1999; 16(5 Part 1): 499-520 Other publications of related interest Grossman R, Mukherjee J, Vaughan D et al. A 1-year community-based health economic study of ciprofloxacin vs. usual antibiotic treatment in acute exacerbations of chronic bronchitis. CHEST 1998;113:131-141.
Indexing Status Subject indexing assigned by NLM MeSH Adult; Anti-Infective Agents /economics /therapeutic use; Bronchitis /classification /drug therapy /economics; Canada; Chronic Disease; Ciprofloxacin /economics /therapeutic use; Cost-Benefit Analysis; Economics, Pharmaceutical; Female; Humans; Male; Prospective Studies; Quality-Adjusted Life Years; Severity of Illness Index AccessionNumber 21999008339 Date bibliographic record published 31/10/2000 Date abstract record published 31/10/2000 |
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