COST-EFFECTIVENESS OF CERVICAL CANCER PREVENTION STRATEGIES IN THAILAND

   Purpose:   Previous studies have assessed the cost-effectiveness of new screening strategies in Thailand, and have motivated initial scale-up of successful demonstration projects. The availability of an effective vaccine against HPV 16 and 18,  two of the most common viral types causing cervical cancer, present decision makers with questions about the optimal cervical cancer prevention program. Our objective was to assess the health and economic outcomes associated with vaccinating pre-adolescent girls, with and without screening.

    Methods:   We used likelihood-based methods to calibrate a first-order Monte Carlo simulation model of the natural history of HPV-induced cervical carcinogenesis to epidemiological data in Thailand. Analyses were conducted using a sample of 50 good-fitting parameter sets. Strategies included HPV vaccination of 9-year-old girls, screening with HPV DNA testing (3 times per lifetime or every 5 years) beginning at age 35, and combinations of these strategies. Costs were expressed in 2005 international dollars and based on primary data and previously published analyses. Sensitivity analyses were conducted varying coverage rates, vaccine efficacy, duration of immunity and cost per-vaccinated girl (including three doses, wastage, support, and programmatic costs).

    Results:   Pre-adolescent vaccination at 70% coverage provided a mean reduction in the lifetime risk of cancer of 49%. Vaccination followed by screening later in life, beginning at age 35, provided a mean reduction of 61%. When the cost per-vaccinated girl was $10 or less (implying $2 per dose), vaccination alone was cost saving, compared to no intervention. When the cost per-vaccinated girl was less than $40, all strategies involving screening alone were dominated by either vaccination alone or HPV DNA testing in combination with vaccination, with incremental ratios of $800 and $4000 per year of life saved (YLS), respectively. As the cost per-vaccinated girl exceeded $100, all vaccination strategies were dominated, or had cost-effectiveness ratios that exceeded a per capita GDP threshold.  

    Conclusions: Provided high coverage of adolescents can be achieved, and vaccine costs are dramatically lowered, pre-adolescent vaccination in Thailand could reduce cervical cancer mortality considerably.  With an annual health expenditure of $70 per capita, both the cost-effectiveness and affordability of this vaccine will require that prices be lowered.