Sunday, October 23, 2011
Grand Ballroom AB (Hyatt Regency Chicago)
Poster Board # 1
(ESP) Applied Health Economics, Services, and Policy Research

Candidate for the Lee B. Lusted Student Prize Competition

Monisha Sharma, ScM, Stephen Sy, BS and Jane J. Kim, PhD, Harvard School of Public Health, Boston, MA

Purpose:   Cervical cancer, caused by sexually-transmitted human papillomavirus (HPV) infections, is the most common form of cancer among women in South Vietnam.  We sought to evaluate the additional health benefits and incremental cost-effectiveness of including boys in an HPV vaccination program of girls in South Vietnam.

Methods:  Sexual transmission of HPV-16 and -18, two of the most common types that cause cervical cancer, was simulated using a dynamic model that was calibrated to the setting of South Vietnam, using epidemiological data on cervical cancer incidence and HPV-16, -18 prevalence, country-specific population statistics, and survey data on heterosexual behavior, including male visits to female sex workers. Predictions of HPV incidence reduction from the model, including direct and indirect (herd immunity) benefits under various scenarios of vaccination, were used as inputs into a first-order Monte Carlo simulation model of HPV and cervical carcinogenesis, which was also calibrated to South Vietnam. Strategies included vaccination of pre-adolescent girls and boys compared with vaccination of girls alone under varied assumptions of vaccine uptake (25%-95%). We assumed vaccine efficacy against HPV-16,-18 infections was 100% for girls and 85% for boys over their lifetime. Sensitivity analyses were conducted on vaccine cost and sexual behavior, including number of sexual partners and mixing patterns in the population.

Results:   Across the range of vaccination coverage levels, vaccinating girls alone consistently resulted in cost-effectiveness ratios less than Vietnam’s per-capita GDP (I$2,682), provided vaccine costs were low (e.g., $10 per-vaccinated individual, or $2 per dose), indicating good value for money.  Although including boys in the vaccination program resulted in higher benefits, the cost-effectiveness ratio exceeded per-capita GDP when the cost was $25 per-vaccinated individual or higher.  For example, when vaccination coverage was 50%, vaccination of girls and boys cost over I$8,000 and I$12,000 per quality-adjusted life year (QALY) gained when vaccine cost was I$50 and I$75, respectively. Reducing the number of sexual partners had a larger impact on cost-effectiveness ratios than assuming less random mixing in the population, but results remained robust under varied assumptions of changes in sexual behavior.

Conclusions:   The optimal target population for HPV vaccination in South Vietnam may not include boys unless HPV vaccine costs are dramatically reduced.