Cost-effectiveness of human papillomavirus vaccination for prevention of cervical cancer in Taiwan

Abstract

Background: Human papillomavirus (HPV) infection has been shown to be a major risk factor for cervical cancer. Vaccines against HPV-16 and HPV-18 are highly effective in preventing type-specific HPV infections and related cervical lesions. There is, however, limited data available describing the health and economic impacts of HPV vaccination in Taiwan. The objective of this study was to assess the cost-effectiveness of prophylactic HPV vaccination for the prevention of cervical cancer in Taiwan.

Methods: We developed a Markov model to compare the health and economic outcomes of vaccinating preadolescent girls (at the age of 12 years) for the prevention of cervical cancer with current practice, including cervical cytological screening. Data were synthesized from published papers or reports, and whenever possible, those specific to Taiwan were used. Sensitivity analyses were performed to account for important uncertainties and different vaccination scenarios.

Results: Under the assumption that the HPV vaccine could provide lifelong protection, the massive vaccination among preadolescent girls in Taiwan would lead to reduction in 73.3% of the total incident cervical cancer cases and would result in a life expectancy gain of 4.9 days or 8.7 quality-adjusted life days at a cost of US$324 as compared to the current practice. The incremental cost-effectiveness ratio (ICER) was US$23,939 per life year gained or US$13,674 per quality-adjusted life year (QALY) gained given the discount rate of 3%. Sensitivity analyses showed that this ICER would remain below US$30,000 per QALY under most conditions, even when vaccine efficacy was suboptimal or when vaccine-induced immunity required booster shots every 13 years.

Conclusions: Although gains in life expectancy may be modest at the individual level, the results indicate that prophylactic HPV vaccination of preadolescent girls in Taiwan would result in substantial population benefits with a favorable cost-effectiveness ratio. Nevertheless, we should not overlook the urgency to improve the compliance rate of cervical screening, particularly for older individuals.

Figure 1

The Markov decision model. The square on the left represents the prophylactic vaccination decision. Each woman's health is tracked by a Markov model after entering the Markov tree (denoted by circles containing an alphabet 'M'). In each cycle, women are at risk of developing oncogenic human papillomavirus (HPV) infection, SIL (squamous intraepithelial lesions), cervical cancer or mortality. The Markov tree branches with ends of rectangles represent the above clinical events that can occur during each 1-year period as a 12-year-old girl is followed until death.

Figure 2

Calibration results of age-specific incidence and mortality of cervical cancer. The circles and bars represent the observed cancer incidence and mortality from the National Cancer Registry of Taiwan, respectively. The squares and hollow bars represent the predicted cancer incidence and mortality by the Markov model in which the current practice of cervical screening was applied from 30 years of age without vaccination.

Figure 3

One-way sensitivity analyses on the incremental cost-effectiveness ratio (ICER). The range of input parameter for the sensitivity analysis is indicated in the parentheses on the left of the vertical axis. The vertical line represents the ICER under base case assumptions. The numbers in brackets alongside the bar represent the ratio between the maximum value (right) and the minimum one (left) in sensitivity analysis respectively over the base case ICER.

Figure 4

Sensitivity analysis of the incremental cost-effectiveness of vaccination compared to the current practice, with respect to the change in human papillomavirus (HPV) vaccine efficacy and immunity longevity. The squares represent a vaccine providing lifetime immunity to HPV-16 and HPV-18 (base case assumption). The triangles represent a vaccine that requires booster shots every 20 years to remain effective. The circles represent a vaccine that needs booster shots every 10 years to maintain effectiveness.