Cost-Effectiveness Analysis of Inhaled Zanamivir in the Treatment of Influenza A and B in High-Risk Patients
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Objective: To evaluate the cost effectiveness of zanamivir 10mg twice daily for 5 days in the treatment of influenza in high-risk patients.
Design: Bootstrap cost-effectiveness analysis incorporating within-trial analysis of pooled patient-level cost and effect data.
Setting: UK unit costs and utilities applied to high-risk patients drawn from 6 multinational clinical trials.
Patients: A total of 154 zanamivir and 167 placebo high-risk patients were included in the analysis.
Main outcome measures: Cost per day of normal activities; cost per symptom-free day; cost per complication averted; cost per quality-adjusted life-year (QALY).
Results: The mean benefit was estimated to be 2.5 days [95% confidence interval (CI): 0.68 to 4.27] of normal activities gained; 2.0 (95% CI: 0.56 to 3.51) symptom-free days; and a 9% reduction in complications (95% CI: 0 to 18%). Excluding the effect of rare hospitalisation costs, the cost (1999 values) of gaining a day of normal activities was £9.50 (95% CI: £5 to £39); cost per symptom-free day was £11.56 (95% CI: £6 to £43); cost per complication averted was £262 (95% CI: £90 to £1574). Influenza was estimated to reduce utility by 0.883 per day, demonstrating the debilitating effect of the disease. Extrapolating a day of normal activities to a standard utility measure resulted in a cost per QALY of £3900 excluding inpatient costs (£7490 including inpatient costs). Cost-effectiveness acceptability curves demonstrated 90% certainty that zanamivir would be cost effective at £8000 per QALY.
Conclusions: Significant health benefits can be obtained with zanamivir treatment in high-risk patients. The cost per QALY for zanamivir in these patients compares well with that of other commonly used pharmacological interventions.
KeywordsChronic Obstructive Pulmonary Disease Influenza Oseltamivir Zanamivir Diary Card
We thank Andrew Briggs (Institute of Health Sciences, University of Oxford); Neil Dobson; Rebecca Warren; and Sophie Hall (GlaxoWellcome UK, Stockley Park, UK). A.D. Griffin and A.S. Perry conceived, designed and performed the economic evaluation. D.M. Fleming conducted the utility measurement in influenza patients and contributed to interpretation of clinical data. A.D. Griffin and A.S. Perry drafted the manuscript and D.M. Fleming critically reviewed it. All authors had final approval of the manuscript. D.M. Fleming serves as a consultant advisor to GlaxoWellcome in relation to their clinical trial programme for zanamivir. He has also received honoraria in respect of lecture presentations on influenza-related issues and for service on advisory boards to the pharmaceutical industry covering influenza vaccination and treatment.
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