Post-exposure influenza prophylaxis with oseltamivir: cost effectiveness and cost utility in families in the UK.

objectivesTo assess the cost effectiveness and cost utility of preventing post-exposure influenza infection using the neuraminidase inhibitor oseltamivir from a healthcare payer's perspective in the UK.

methodsA simulation model was developed, based on clinical trial results and published data, to predict morbidity and mortality due to influenza and to compare oseltamivir post-exposure prophylaxis (PEP) with no prophylaxis within families with members aged >or=13 years. Two scenarios were tested:1. Comparison of patients receiving PEP versus patients not receiving PEP and not being treated with oseltamivir should they become infected. 2. Comparison of patients receiving PEP versus patients not receiving PEP but being treated with oseltamivir should they become infected. The model was run with an attack rate in household contacts of 8% for the base case, with higher rates (up to 30%, representing pandemic conditions) tested in sensitivity analyses. A societal perspective and other key parameters were tested in sensitivity analysis. The year of costing was 2002. The time span for the model was up to 1 year (including one influenza season), but loss of life was included in the QALY calculation and based on expected life expectancy.

resultsPEP with oseltamivir results in reduced morbidity (i.e. fewer influenza cases) and associated reductions in complications, hospitalisations and mortality due to influenza. When comparing oseltamivir PEP with no prophylaxis for contact attack rates of 8%, 12% and 30%, the mean costs per QALY gained for scenario one were estimated at 29,938 pounds, 18,697 pounds and 5403 pounds, respectively; the mean costs per case avoided were 467 pounds, 293 pounds and 84 pounds, respectively. The corresponding results for scenario two were 52,202 pounds, 31,610 pounds and 9688 pounds per QALY gained.

conclusionsPEP with oseltamivir is likely to be a cost-effective strategy for family contacts in the UK from a healthcare payer perspective when influenza-like illness contact attack rates are 8% or higher and the only treatment given is 'usual care'.