Management of influenza symptoms in healthy adults - Cost-effectiveness of rapid testing and antiviral therapy

OBJECTIVE: To determine the cost-effectiveness of rapid diagnostic testing and empiric antiviral therapy for healthy adults with symptoms of influenza. DESIGN: Cost-effectiveness analysis using a decision model based on previously published data. Outcome measures included costs and quality-adjusted life expectancy. SETTING: Physician's office. PATIENTS/PARTICIPANTS: Hypothetically healthy, working adults < 65 years of age presenting with cough and fever during the influenza season. INTERVENTIONS: Rapid testing or clinical diagnosis followed by treatment with amantadine, rimantadine, oseltamivir, or zanamivir compared with no antiviral therapy. RESULTS: Base-case analysis: not giving antiviral therapy is the most expensive and least effective strategy, costing $471 per patient, mostly owing to time lost from work. Amantadine treatment increases life expectancy by 0.0014 quality-adjusted life years (QALYs) while saving $108 per patient relative to no antiviral therapy. Zanamivir is slightly more effective than amantadine, adding 0.0002 QALYs at an incremental cost of $31, or $133,000 per QALY saved. All other strategies, including testing strategies, are both less effective and more expensive. SENSITIVITY ANALYSIS: The model is sensitive to the probability of influenza infection, proportion of influenza caused by type B, the relative efficacy of the various drugs, and the value of a workday. At a clinical probability of influenza infection > 20%, antiviral therapy is favored. As the proportion of influenza B increases, zanamivir is favored over amantadine. Testing is rarely indicated. Ignoring the costs of lost workdays, amantadine treatment costs $1,200/QALY saved. CONCLUSIONS: Antiviral therapy with either amantadine or zanamivir is cost-effective for healthy, young patients with influenza-like illness during the influenza season, depending on the prevalence of influenza B.