A cost-benefit analysis of testing for influenza A in high-risk adults.

BACKGROUND Clinical diagnosis and empiric therapy have been strategies for treatment of suspected influenza in high-risk patients, but rapid tests for influenza have been introduced to help confirm cases. The aim of this study was to determine when rapid testing, empiric treatment, or no treatment is most cost-beneficial for high-risk adults with influenzalike respiratory tract illnesses. METHODS We performed a cost-benefit analysis evaluating the comparative advantage of the strategies of empiric therapy, no treatment, or test and treat patients whose tests are positive. The analysis focused on a hypothetical population of patients who are at a high-risk for complications of influenza. Our main outcome was the cost of care for an episode of influenza taken from the human capital perspective. RESULTS For older anti-influenza drugs (amantadine and rimantadine), rapid testing is not as cost-beneficial as empiric treatment, even when the prevalence of influenza is low. For the neuraminidase inhibitors, there is a narrow window of disease prevalence between 30% and 40% where testing is most cost-beneficial. When the disease likelihood is above this window, empiric treatment is preferred. Below this window, no treatment is more cost-beneficial. Even under the most favorable conditions, testing is preferred only for a small range of prevalence rates of influenza. CONCLUSION When clinicians are planning to use the nonneuraminidase inhibitors to treat influenza, rapid testing is not the most cost-beneficial approach. Even when the more expensive neuraminidase inhibitors will be used, testing has a limited role in managing influenza in high-risk patients.