CHDS faculty conducts analysis to inform policy decisions in U.S.

Core CHDS faculty member, Jane Kim, presented an influential analysis in three venues to inform policy - these meetings included one focusing on decision scientific methods, one informing clinical guidelines for screening in the U.S., and finally, the Advisory Committee on Immunization Practices (ACIP) of the CDC. Her main message was straightforward. "The cost-effectiveness of vaccination in the United States against human papillomavirus (HPV) will be optimized by achieving universal vaccine coverage in young adolescent girls, by targeting initial "catch-up" efforts to vaccinate women younger than 21 years of age, and by revising current screening policies."

Cervical cancer is caused by sexually-transmitted infection with high-risk "oncogenic" types of HPV, also associated with other cancers. In the U.S., cervical cancer kills more than 3,000 women per year. Secondary prevention has relied on a screening program involving frequent cytology (Pap smear) and/or HPV DNA testing, recommended annually or biennially for sexually-active women. HPV vaccination raises questions regarding the age at which to vaccinate females, target groups for temporary catch-up programs, and appropriate changes to screening practices. Vaccines against HPV-16 and HPV-18 appear to be highly efficacious in preventing HPV-16 and HPV-18 infections and cervical disease in females who have not previously been infected with these types. The quadrivalent vaccine also prevents low risk HPV types 6 and 11 (HPV-6 and HPV-11) infections, which are responsible for most genital warts and juvenile-onset recurrent respiratory papillomatosis.

Professor Kim used computer-based models within a decision analytic framework to synthesize epidemiologic, clinical, and demographic information. Her analysis estimated the health and economic outcomes of HPV vaccination of preadolescent girls (i.e., 12 years of age) and catch-up vaccination over a 5-year period for girls and women over 12 years of age, in the context of routine cervical cancer screening; strategies differed in the upper age of catch-up programs, to ages 18, 21, or 26 years. A novel part of this study involved examining how uncertain scenarios might impact the appropriate policies for the U.S., such as the duration of vaccine protection and whether or not a booster dose will be needed, whether or not the vaccine will also prevent infections with other HPV types, and what might occur to rates of cancer if women change their screening practices after being vaccinated.

Kim reported at several national meetings, as well as at the Advisory Committee on Immunization Practices (ACIP), that vaccination against HPV-16 and HPV-18 would lead to lower cervical cancer rates and be economically attractive if high coverage can be achieved in the most important target group of 12-year-old girls, and if vaccine protection against infection lasted for at least 20 years. She also found that future cervical cancer screening could begin somewhat later than currently recommended and be conducted less frequently (i.e., every 3 to 5 years). In agreement with current guidelines, she found a catch-up program for girls between 13 and 18 years of age provided additional benefits and was reasonably cost-effective compared to other vaccine programs in the U.S. However, in contrast to U.S. guidelines for HPV vaccination, she found that the cost-effectiveness of extending the catch-up program to 21 years of age was less certain, and depended on whether the vaccine would eventually be proven to prevent other cancers caused by HPV-16 and -18. The analytic work described was funded by the National Cancer Institute, the Centers for Disease Control and Prevention, and the American Cancer Society. The article, "Health and economic implications of HPV vaccination in the United States," appeared in The New England Journal of Medicine, August 21, 2008, Volume 359, Number 8. An editorial, "Human Papillomavirus Vaccination — Reasons for Caution," appeared in the same issue.