Cost-Effectiveness of Antiviral Drug Stockpiling and Near Patient Testing for Pandemic Influenza

Abstract:     
Many countries are stockpiling antiviral (AV) drugs in preparation for a possible influenza pandemic. This study investigated the cost-effectiveness of such a strategy and the role of near-patient testing in conserving AV stocks, using a decision-analytical model. Under base-case assumptions (which included a fixed stockpile size that was smaller than the clinical attack rate) treating all symptomatic patients ('Treat Only') would be considered cost-effective (approximately £1,900-£13,800 per QALY gained, depending on the mortality scenario) compared with 'Do Nothing'. The 'Test-Treat' option (testing all symptomatic patients but treating only those that tested positive) resulted in moderate gains in QALYs at relatively large additional costs. The cost-effectiveness of 'Treat Only' was very sensitive to AV efficacy in preventing deaths. The model was also moderately sensitive to the time delay to the next pandemic and the discount rate. Other parameters (such as efficacy against complications, or the overall clinical attack rate) were not important determinants of the cost-effectiveness of this strategy. In the long-run the size of the antiviral and near-patient test stockpiles can be altered. Under these circumstances the optimum strategy involves stockpiling adequate AVs to treat all symptomatic cases (those with pandemic influenza and influenza-like illness) and cover any AV wastage in the programme. Strategies involving stockpiling near-patient tests are not on the efficiency frontier. Indeed, if the antiviral stockpile exceeds the total demand (overall number experiencing illness plus wastage), then testing of patients results in a loss of QALYs (i.e. is dominated by treatment only), unless the test is 100% sensitive. Stockpiling sufficient antivirals to treat all clinical cases appears to be a cost-effective strategy, provided antivirals are effective at preventing deaths from pandemic influenza. Stockpiling near-patient tests is not cost-effective.

Keywords: pandemic influenza, infectious diseases, economic analysis

JEL Classification: I18

working papers series