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

2 September 2003 | Volume 139 Issue 5 Part 1 | Pages 321-329

Background: Although antiviral therapy is cost-effective in adults, its cost-effectiveness in older adults has not been studied.

Objective: To determine the cost-effectiveness of influenza testing and treatment strategies for older adults.

Design: Cost–utility decision model.

Data Sources: Clinical trials of antiviral drugs and epidemiologic data.

Target Population: Noninstitutionalized adults older than 65 years of age with influenza-like illness.

Time Horizon: Lifetime.

Perspective: Societal.

Interventions: Rapid diagnostic testing or empirical therapy with antiviral drugs.

Outcome Measures: Cost per quality-adjusted life-year (QALY) saved.

Results of Base-Case Analysis: 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.

Results of Sensitivity Analysis: 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.

Conclusions: 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.

Editors' Notes Context Drugs to treat influenza are cost-effective in adults younger than 65 years of age, but the cost-effectiveness of these drugs for people older than 65 years is unknown. Contribution For unvaccinated persons older than 65 years of age with influenza-like illness, empirical treatment with amantadine cost $1129 per quality-adjusted life-year (QALY), treatment with oseltamivir after rapid diagnostic testing cost $5025 per QALY, and empirical treatment with oseltamivir cost $10 296 per QALY. The cost-effectiveness of all strategies was less favorable for vaccinated patients but was always $70 300 or less per QALY. Implications Antiviral drugs are cost-effective for patients older than 65 years of age who develop influenza-like illness. Physicians should choose amantadine or oseltamivir, empirically or after rapid diagnostic testing, after considering patients' vaccination status, comorbidity level, and ability to pay for the drugs. –The Editors

 

Author and Article Information

From Baystate Medical Center, Springfield, Massachusetts; and Tufts University School of Medicine, Boston, Masssachusetts.

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: Michael Rothberg, MD, MPH, Division of General Medicine and Geriatrics, Baystate Medical Center, 759 Chestnut Street, Springfield, MA 01199; e-mail, Michael.Rothberg{at}bhs.org.

Current Author Addresses: Drs. Rothberg, Bellantonio, and Rose: Division of General Medicine and Geriatrics, Baystate Medical Center, 759 Chestnut Street, Springfield, MA 01199.

Author Contributions: Conception and design: M.B. Rothberg, D.N. Rose.

Analysis and interpretation of the data: M.B. Rothberg, D.N. Rose.

Drafting of the article: M.B. Rothberg, S. Bellantonio, D.N. Rose.

Critical revision of the article for important intellectual content: M.B. Rothberg, S. Bellantonio, D.N. Rose.

Final approval of the article: M.B. Rothberg, S. Bellantonio, D.N. Rose.

Statistical expertise: M.B. Rothberg, D.N. Rose.

Administrative, technical, or logistic support: D.N. Rose.

Collection and assembly of data: M.B. Rothberg.