Cost-Effectiveness of a Vaccine To Prevent Herpes Zoster and Postherpetic Neuralgia in Older Adults

5 September 2006 | Volume 145 Issue 5 | Pages 317-325

Background: The Shingles Prevention Study showed that a varicella-zoster virus (VZV) vaccine administered to adults 60 years of age or older reduced the incidence of herpes zoster from 11.12 to 5.42 cases per 1000 person-years. Median follow-up was 3.1 years, and relative risk reduction was 51.3% (95% CI, 44.2% to 57.6%).

Objective: To assess the extent to which clinical and cost variables influence the cost-effectiveness of VZV vaccination for preventing herpes zoster in immunocompetent older adults.

Design: Decision theoretical model.

Data Sources: English-language data published to March 2006 identified from MEDLINE on herpes zoster rates, vaccine effectiveness, quality of life, medical resource use, and unit costs.

Target Population: Immunocompetent adults 60 years of age or older with a history of VZV infection.

Time Horizon: Lifetime.

Perspective: U.S. societal.

Interventions: Varicella-zoster virus vaccination versus no vaccination.

Outcome Measures: Incremental quality-adjusted survival and cost per quality-adjusted life-year (QALY) gained.

Results of Base-Case Analysis: By reducing incidence and severity of herpes zoster, vaccination can increase quality-adjusted survival by 0.6 day compared with no vaccination. One scenario in which vaccination costs less than $100 000 per QALY gained is when 1) the unit cost of vaccination is less than $200, 2) the age at vaccination is less than 70 years, and 3) the duration of vaccine efficacy is more than 30 years.

Results of Sensitivity Analysis: Vaccination would be more cost-effective in "younger" older adults (age 60 to 64 years) than in "older" older adults (age 80 years). Longer life expectancy and a higher level of vaccine efficacy offset a lower risk for herpes zoster in the younger group. Other factors influencing cost-effectiveness include quality-of-life adjustments for acute zoster, unit cost of the vaccine, risk for herpes zoster, and duration of vaccine efficacy.

Limitations: The effectiveness of VZV vaccination remains uncertain beyond the median 3.1-year duration of follow-up in the Shingles Prevention Study.

Conclusions: Varicella-zoster virus vaccination to prevent herpes zoster in older adults would increase QALYs compared with no vaccination. Resolution of uncertainties about the average quality-of-life effects of acute zoster and the duration of vaccine efficacy is needed to better determine the cost-effectiveness of zoster vaccination in older adults.

Editors' Notes Context A recent large trial proved that a live attenuated varicella-zoster virus vaccine reduced the incidence and severity of herpes zoster in older adults. Contribution This decision model suggests that vaccination could improve quality-adjusted survival by small amounts. Vaccination is, however, unlikely to cost less than $100 000 per quality-adjusted life year gained unless the vaccination cost is less than $200 and duration of vaccine efficacy exceeds 20 years. Targeting adults 60 to 69 years of age rather than those older than 80 years of age would be most cost-effective. Cautions We do not yet know how long the vaccine remains effective. —The Editors

 

Author and Article Information

From the SPHERE Institute and Acumen LLC, Burlingame, California; Veterans Affairs Palo Alto Health Care System, Palo Alto, California; and Stanford University School of Medicine, Stanford, California.

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: John Hornberger, MD, MS, Acumen LLC, 500 Airport Boulevard, Suite 365, Burlingame, CA 94010; e-mail, jhornberger{at}acumen-llc.com.

Current Author Addresses: Dr. Hornberger and Ms. Robertus: Acumen LLC, 500 Airport Boulevard, Suite 365, Burlingame, CA 94010.

Author Contributions: Conception and design: J. Hornberger.

Analysis and interpretation of the data: J. Hornberger, K. Robertus.

Drafting of the article: J. Hornberger.

Critical revision of the article for important intellectual content: J. Hornberger, K. Robertus.

Final approval of the article: J. Hornberger, K. Robertus.

Provision of study materials or patients: J. Hornberger.

Statistical expertise: J. Hornberger, K. Robertus.

Obtaining of funding: J. Hornberger.

Administrative, technical, or logistic support: J. Hornberger.

Collection and assembly of data: J. Hornberger, K. Robertus.