REPLY
Cost and Effectiveness of Hepatitis B Immunization
Bernard S. Bloom;
Alan J. Hillman;
A. Mark Fendrick; and
J. Sanford Schwartz
15 September 1993 | Volume 119 Issue 6 | Pages 536-537
IN RESPONSE:
We agree with Dr. Asch that we probably underestimated the cost-effectiveness of hepatitis B virus vaccination by not incorporating the effects of herd immunity in our analysis [1]. We also agree that quantifying the effects of herd immunity is extremely difficult when examining any vaccination strategy. Our study evaluated three strategies (universal vaccination, screening and vaccination of those with negative test results, no vaccination) in four populations (newborns, adolescents, general adults, high-risk adults).
We took conservative positions wherever possible; that is, we purposely underestimated benefits and increased costs, thereby reducing cost-effectiveness ratios of all vaccination strategies examined. We chose to determine clinical and economic outcomes of hepatitis B virus vaccination under "worst case" assumptions [2]. The results indicating cost-effectiveness of selected vaccination strategies are thus robust. Omitting the effects of herd immunity is consistent with this position.
Three effects of such a conservative position should be noted. First, including effects of herd immunity would not have changed the study conclusion that universal hepatitis B virus vaccination is highly cost-effective. Second, our study results should be viewed as incremental, defining cost-effectiveness of the various vaccination strategies we studied before herd immunity is established. Third, the more optimistic assumptions suggested by Dr. Asch would improve the cost-effectiveness of the recommended strategies.
The burden of proof is always on the proponent of an intervention. When conservative assumptions produce highly cost-effective results, the decision maker can be confident that the estimate will be the lowest that can be expected. Greater population benefits at no increased cost accruing in the real world of medical practice are a bonus. Our conservative conclusions indicate that there is no clinical or economic reason to delay or deny investing in protecting children and adolescents from hepatitis B virus.
1. Bloom BS, Hillman AL, Fendrick AM, Schwartz JS. A reappraisal of hepatitis B virus vaccination using cost-effectiveness analysis. Ann Intern Med. 1993; 118:298-306.
2. Hillman AL, Eisenberg JM, Pauly MV, Bloom BS, Glick H, Kinosian B, et al. Avoiding bias in the conduct of cost-effectiveness research sponsored by pharmaceutical companies. N Engl J Med. 1991; 324: 1362-5.
About Letters
The Editors welcome submissions for possible publication in the Letters section. Authors of letters should:
•Include no more than 300 words of text, three authors, and five references
•Type with double-spacing
•Send three copies of the letter, an authors' form signed by all authors, and a cover letter describing any conflicts of interest related to the contents of the letter.
Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
Annals welcomes electronically submitted letters.
Top
References
Article
