Effectiveness and cost-effectiveness of human papillomavirus (HPV) vaccines in cervical cancer prophylaxis (Thesis)

Abstract

Human papillomavirus (HPV) infection is the main cause of cervical cancer. Cervical cancer patients go through painful long-term treatments and high medical costs. Prevention is better than cure. Hence, regular cervical screening is recommended for women to prevent this disease. HPV vaccinations were first introduced in the market in 2006, and they have been proven to have high efficacy. Some studies have been conducted in Western countries to determine the cost-effectiveness of HPV vaccinations. Results show that cost-effectiveness can be achieved by combining HPV vaccines with regular screening. In the current thesis, a theoretical framework is employed in the analysis and discussion, combining the concepts from both welfare economics and the cost-effectiveness analysis technique. Welfare economics is a branch of economics focusing on resource allocation efficiency and optional income distribution of an economy. It forms the foundation of cost-effectiveness analysis (CEA) because it guides in the understanding of important concepts, such as the use of disability-adjusted life years (DALYs) measurement, which measures the overall burden of disease. Welfare economics can also reveal surprising information about the health of a population. The study is guided by three research groups on the future implication of the cost-effectiveness of three cervical cancer prevention strategies: (1) annual Pap smear for women aged 2542, (2) HPV vaccination at age 12, and (3) HPV vaccination at age 12 combined with annual Pap smear screening at age 2542. The three groups are compared in terms of their cost-effectiveness ratio and incremental life expectancy. The samples chosen for the study are 12-year-old female Hong Kong residents in 2006. Previous studies have established that 12-year-old girls are suitable participants in the cost-effectiveness analysis of HPV vaccines. Local data are mainly drawn from the Census and Statistics Department, Hong Kong Government (n = 40, 835). The Markov model software is used as the main analytical tool. The Markov cohort analysis is employed for data analysis in this present study. In the discussion section, important issues concerning the three study groups are discussed and analysed, including cost-effectiveness ratio, incremental cost, and incremental life expectancy. The current study determines that, among participants assumed to have been infected by either HPV 16/18 and have natural immunity or other high-risk HPV genotypes and have no natural immunity who had annual Pap smear screening at age 2542, cost increased to approximately USD145.69; effect was 83.26 DALY; cost-effectiveness ratio was USD8.80/DALY; life expectancy was 17.8806 years; and incremental life expectancy was 2.7151 years.

Among participants who had HPV vaccination at age 12, cost increased to approximately USD437.27; effect was 83.26 DALY; cost-effectiveness ratio was USD23.05/DALY. The life expectancy was 18.0000 years; and incremental life expectancy was 2.8345 years, provided that these participants assumed to have been infected by HPV 16 and 18 and have natural immunity. The life expectancy was 17.9334 years; and incremental life expectancy was 2.7679 years, provided that these participants assumed to have been infected by other high-risk HPV genotypes and have no natural immunity. Among participants who had HPV vaccination at age 12, combined with annual Pap smear screening at age 2542 and providing that they assumed to have been infected by HPV 16/18 and have natural immunity, cost increased to approximately USD545.12; effect was 83.26 DALY; cost-effectiveness ratio was USD29.56/DALY; life expectancy was 18.0000 years; and incremental life expectancy was 2.8345 years. Among participants who had HPV vaccination at age 12, combined with annual Pap smear screening at age 2542 and providing that they assumed to have been infected by other high-risk HPV genotypes and have no natural immunity, cost increased to approximately USD545.18; effect was 83.26 DALY; cost-effectiveness ratio was USD29.56/DALY; life expectancy was 17.9975 years; and incremental life expectancy was 2.8320 years. To conclude, annual Pap smear screening is a cost-effective method to prevent cervical cancer. Moreover, HPV vaccination associated with annual Pap smear screening is an effective way to prolong the life expectancy of Hong Kong women. Such result provides important insight for the formulation of a health care policy to prevent cervical cancer in Hong Kong. This policy can save lives and reduce local treatment costs. The results of this study are similar to those of the studies conducted in Japan and Western countries. Thus, HPV vaccination associated with annual Pap smear screening can be concluded to be an effective way of prolonging the life expectancy of women regardless of race. Moreover, the result can push the government to consider introducing the HPV vaccine into its current childhood immunisation programme. The HPV vaccine has demonstrated its cost-effectiveness as a cervical cancer prevention method and is an effective way to prolong the life expectancy of Hong Kong women.