Management of Influenza in Adults Older than 65 Years of Age: Cost-Effectiveness of Rapid Testing and Antiviral Therapy

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Abstract
Although antiviral therapy is cost-effective in adults, its cost-effectiveness in older adults has not been studied. To determine the cost-effectiveness of influenza testing and treatment strategies for older adults. Costutility decision model. Clinical trials of antiviral drugs and epidemiologic data. Noninstitutionalized adults older than 65 years of age with influenza-like illness. Lifetime. Societal. Rapid diagnostic testing or empirical therapy with antiviral drugs. Cost per quality-adjusted life-year (QALY) saved. Compared with no intervention, empirically treating an unvaccinated 75-year-old patient with amantadine increased life expectancy by 0.0014 QALY at a cost of $1.57, a cost-effectiveness ratio of $1129 per QALY saved. Compared with amantadine, rapid diagnostic testing followed by treatment with oseltamivir cost $5025 per QALY saved and empirical treatment with oseltamivir cost $10 296 per QALY saved. Testing and treatment strategies were less cost-effective if the patient was vaccinated, ranging from $2483 per QALY saved with amantadine to $70 300 per QALY saved with oseltamivir. The decision was sensitive to the probability of influenza, the efficacy of oseltamivir in preventing hospitalizations, and hospitalization and case-fatality rates. The decision was not sensitive to the probability or severity of medication side effects, the quality of life for influenza illness or hospitalization, the efficacy of antiviral therapy in shortening influenza illness, or the rapid diagnostic test characteristics. For unvaccinated or high-risk vaccinated patients during the influenza season, empirical oseltamivir treatment is cost-effective. For other patients, rapid diagnostic testing followed by treatment with oseltamivir is cost-effective. Empirical amantadine treatment offers a low-cost alternative if patients cannot afford oseltamivir.