Cost-effectiveness study eyes HPV vaccine

What is the most cost-effective approach to administering vaccination against human papillomavirus (HPV)? A just-released analysis concludes vaccination will be optimized by achieving universal vaccine coverage in young adolescent girls, targeting initial "catch-up" efforts to vaccinate women younger than age 21, and by revising current screening policies.1

Gardasil (Merck & Co., Whitehouse Station, NJ) is the only HPV vaccine approved by the Food and Drug Administration (FDA). It is designed to protect against infection from four HPV types, including two types (HPV 16 and 18) that cause about 70% of cervical cancers. The vaccine received an additional approval in September 2008 for the prevention of vaginal and vulvar cancer caused by HPV types 16 and 18.2 Given in three doses over six months, the vaccine series costs about $360.

Gardasil is approved for women ages 9-26. The Centers for Disease Control and Prevention (CDC) recommends the vaccine for all girls ages 11-12, with "catch-up" doses for those ages 13-26 who missed earlier vaccination.

To perform the analysis, researchers at the Harvard School of Public Health synthesized epidemiologic, clinical, and demographic information using sophisticated computer models to simulate the U.S. population. Researchers designed computer models to predict the health outcomes of girls and women who get the vaccination as well as Pap tests or other screenings, which still are recommended for vaccine recipients. Calculations included the cost of the vaccine, screenings, and treating cervical cancer and other illnesses targeted by the vaccine. While the study focused on the prevention of cervical disease, investigators also looked at the benefits of the vaccine on genital warts and its possible benefits of averting other HPV-related cancers and conditions.

What were the results?

Analysis findings indicate 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. If most 12-year-old girls are vaccinated, their future cervical cancer screening could begin somewhat later than currently recommended and be conducted less frequently, the analysis suggests.

A catch-up program for girls ages 13-18 appears to offer benefits and be reasonably cost-effective, compared to other vaccine programs in the United States, researchers note. The cost-effectiveness of extending the catch-up program to age 21 is less certain and depends on whether the vaccine eventually will be proven to prevent other cancers caused by HPV-16 and -18. Extending the catch-up program to those up to age 26 was consistently not cost-effective due to the vaccine's expense, investigators conclude.

Results of the analysis could change if future information shows that vaccine protection does not last, or if there is an unexpected increase in other cancer-causing HPV types not included in the vaccine, caution the researchers. "Our results are the best prediction we can make with the information available now, but it will be critical to update the analysis as we learn more about the long-term vaccine effects," states Jane Kim, PhD, MSc, assistant professor of health decision science in the Department of Health Policy and Management at Harvard School of Public Health and co-author of the paper.

Why is it so important to continue with the current strategy of universal vaccination with pre-adolescent girls together with a "catch up" program for older females who have not been vaccinated? Gardasil works best when given prior to exposure to HPV types 6, 11, 16, and 18, explains Tracy Ogden, a Merck spokesperson. The optimal administration of the vaccine is before the onset of sexual activity, Ogden notes.

A catch-up vaccination program works because even among those who are sexually active, it is unlikely that anyone would have been exposed to all four types of the HPV virus that Gardasil protects against, states Ogden. People who are infected with one type of HPV still would receive protection from the other three HPV types covered by the vaccine, says Ogden. "That's why the CDC's Advisory Committee on Immunization Practices [ACIP] recommends catch-up vaccination for females aged 13 to 26 years who have not been previously vaccinated," Ogden states.

ACIP has not considered changing its current recommendation for catch-up vaccination of females ages 13-26, according to a press statement issued by the CDC.3 It recently reviewed the HPV cost-effectiveness analysis during its deliberations on recommendations for use of HPV vaccine in women age 27 years and older. The committee continues to review new information and data as they become available.3

Opportunity to discuss contraceptives

The provision of the HPV vaccine for girls ages 11-12 offers family planning programs an important way to serve young girls and initiate at a very young age the discussion of the use of contraception to prevent unintended pregnancy, says Robert Hatcher, MD, MPH, professor of gynecology and obstetrics at Emory University School of Medicine in Atlanta.

"This discussion is one of the most important components of preconceptional care, offering providers the opportunity to discuss the importance of folic acid for all women in their reproductive years, delaying intercourse until a girl is certain that it is something she wants to do, and of course, the use of condoms to prevent infection and other effective contraceptive methods," Hatcher says.

References

  1. Kim JJ, Goldie SJ. Health and economic implications of HPV vaccination in the United States. N Engl J Med 2008; 359:821-832.
  2. Food and Drug Administration. FDA Approves Expanded Uses for Gardasil to Include Preventing Certain Vulvar and Vaginal Cancers. Press release. Sept. 12, 2008. Accessed at www.fda.gov/bbs/topics/NEWS/2008/NEW01885.html.
  3. Centers for Disease Control and Prevention. HPV Vaccine -- Cost-Effectiveness of HPV Vaccine. Press release. Aug. 28, 2008. Accessed at www.cdc.gov/vaccines.