The cost-effectiveness of screening the U.S. blood supply for West Nile virus.

Background: The spread of West Nile virus across North America and evidence of transmission by transfusion prompted the U.S. Food and Drug Administration to encourage the development of methods to screen the blood supply.

Objective: To assess the cost-effectiveness of nucleic acid amplification testing for West Nile virus in the U.S. blood supply.

Design: Markov cohort simulation.

Data Sources: Outcome probabilities estimated from nucleic acid testing done for West Nile virus in 2003, data from the Centers for Disease Control and Prevention, and published literature. Costs were taken from an economic study of West Nile virus infection and from estimated test costs. TARGET POPULATIONS: Transfusion recipients, 60 years of age or older, with and without underlying immunocompromise.

Time Horizon: Lifetime.

Perspective: Societal.

Interventions: The authors compared 6 strategies, taking into consideration minipool (pools of 6 to 16 donations) versus individual donation testing, and the geographic and seasonal nature of West Nile virus activity.

Outcome Measures: Costs and effects of each strategy based on the prevention of transfusion-transmitted West Nile virus.

Results Of Base-case Analysis: The cost-effectiveness of annual, national minipool testing was 483,000 dollars per quality-adjusted life-year (QALY), whereas the cost-effectiveness of annual, national individual donation testing was 897,000 dollars/QALY. The cost-effectiveness of targeted individual donation testing in an area experiencing an outbreak coupled with minipool testing elsewhere was 520,000 dollars/QALY.

Results Of Sensitivity Analysis: In 1-way analyses, the most important influences were the prevalence of West Nile virus and the cost of minipool testing and individual donation testing. The 95% range of results from probabilistic sensitivity analysis for targeted individual donation testing was 256,000 dollars to 1,044,000 dollars/QALY.

Limitations: The outcomes of West Nile virus infection were based on data from the general population rather than from the population who received transfusions. The results are most useful in the context of geographically focused outbreaks of West Nile virus infection.

Conclusions: Using targeted individual donation testing to interdict blood donations that are positive for the West Nile virus is relatively cost-effective but is highly dependent on West Nile virus prevalence.