Assessing the introduction of universal human papillomavirus vaccination for preadolescent girls in The Netherlands

Cost-effectiveness of nonavalent HPV vaccination in the Netherlands

BACKGROUND

A bivalent human papillomavirus vaccine (2vHPV) is currently used in the Netherlands; a nonavalent vaccine (9vHPV) is also licensed.

RESEARCH DESIGN AND METHODS

We compared the public health and economic benefits of 2vHPV- and 9vHPV-based vaccination strategies in the Netherlands over 100 years using a validated deterministic dynamic transmission metapopulation model.

RESULTS

Compared to 2vHPV, the 9vHPV strategy averted an additional 3,245 cases of and 825 deaths from 9vHPV-strain-attributable cancers, 4,247 cases of and 190 deaths from recurrent respiratory papillomatosis (RRP), and 1,009,637 cases of anogenital warts (AGWs), with an incremental cost-effectiveness ratio (ICER) of €4,975 per quality-adjusted life year (QALY) gained. The ICER increased in a scenario with increased HPV vaccination coverage rates and was relatively robust to one-way deterministic sensitivity analyses, with variation in the disease utility parameter having the most impact. When catch-up vaccination for individuals ≤26 years of age was added to the model, vaccinating with 9vHPV averted additional cancers and AGWs compared to 2vHPV vaccination.

CONCLUSION

Our analyses predict that transitioning from a 2vHPV- to a 9vHPV-based vaccination strategy would be cost-effective in the Netherlands.

Ten years of HPV vaccination in the Netherlands: current evidence and future challenges in HPV-related disease prevention

INTRODUCTION

Girls-only vaccination against human papillomavirus (HPV) type 16 and 18 was implemented in the Netherlands in 2009. Despite the evidence of the efficacy against precancerous lesions, cross-protection induced by the vaccine and a greater potential for cancer prevention than cervical cancer only, vaccine coverage in the girls-only program has remained below target levels.

AREAS COVERED

In this paper, we review the literature from the Netherlands on the effectiveness and cost-effectiveness of HPV vaccination since vaccine introduction, give an account of the coverage, safety and effectiveness of HPV vaccination as has been reported in the Dutch surveillance program and discuss challenges of the current HPV vaccination program.

EXPERT COMMENTARY

Girls-only HPV vaccination may confer a substantial health gain in HPV-related disease prevention. However, vaccine coverage declined remarkably recently possibly related to safety concerns, limiting the benefits from girls' vaccination and increasing the potential additional benefit of sex-neutral HPV vaccination. Considering the emergence of novel vaccination and screening options and the change from cytology- to HPV-based screening in 2017, further research is required to inform decisions on the optimization of an integrated vaccination and screening program.

Putting public health infrastructures to the test: introducing HPV vaccination in Austria and the Netherlands

This article presents two cases of policymaking concerning the vaccine against Human Papilloma Virus (HPV), which is sexually transmitted and carcinogenic. Our analysis focuses on its introduction in Austria and the Netherlands. In both contexts, we find prevention and screening to be at once complementary and competing public health logics and we draw on the concept of 'infrastructure' to understand their roles in shaping the reception of the vaccine. We reveal how the HPV vaccine had to be made 'good enough', much like the Pap smear (Casper and Clarke ), by means of diverse tinkering practices that transformed both the technology and the infrastructures in which they emerged. At the same time, it was important that the vaccine would not come to problematise Pap smear-based screening. The article points to the contextually contingent nature of policymaking around new medical technologies, and the skillful care with which public health infrastructures such as immunisation and screening programmes are handled and tinkered with.

Facilitators and barriers to the acceptance of human papillomavirus (HPV) vaccination among adolescent girls: a comparison between mothers and their adolescent daughters in Hong Kong

BACKGROUND

The aim of this study is to examine knowledge and attitude as facilitators and barriers to the acceptance of HPV vaccination for adolescent girls by mothers and adolescent girls.

METHODS

A cross-sectional survey conducted in Hong Kong in January 2010. Adolescent girls aged 12-18, together with their mothers, were recruited to complete two separate questionnaires with similar questions.

RESULTS

A total of 170 mother-adolescent girl dyads were recruited. When the daughters and mothers were compared, the mothers were found to be more aware of "the risk of becoming infected with HPV through early sexual intercourse," while more daughters than mothers knew that "the HPV virus cannot be cured with antibiotics." Significantly more daughters perceived that they had a "chance of being infected with HPV and getting cervical cancer without the vaccine," while more mothers were concerned that "vaccinating for HPV will cause a girl to be stigmatized as promiscuous" and thought that their "adolescent daughters are too young to receive the HPV vaccine." The major predictive factor for the acceptance of the HPV vaccine among mothers was "The HPV vaccine is safe" (OR = 10.126, 95% CI 2.47-41.54). Among daughters who accepted the vaccine, the predictive factor was "The HPV vaccine can prevent most HPV infections" (OR = 6.274, 95% CI 1.93-20.42).

CONCLUSIONS

The findings provide healthcare professionals with a better understanding of the differences between mothers and adolescent girls in knowledge, attitude, and potential factors associated with acceptance of the HPV vaccine. Health professionals should promote the early prevention of HPV infection and eliminate the stigma surrounding HPV vaccination to increase its acceptance. The government should provide financial support for adolescent girls to receive the vaccination in school.

Prevalence of human papillomavirus in head and neck cancers in European populations: a meta-analysis

BACKGROUND

Infection with human papillomavirus (HPV) is necessary for the development of cervical carcinoma. By contrast, the role of HPV in the pathogenesis of other malignancies, such as head and neck cancers, is less well characterised. This study aimed to address key information gaps by conducting a systematic review and meta-analysis of the prevalence of HPV infection in head and neck cancers, focusing on data for European populations.

METHODS

MEDLINE, Embase and grey literature sources were systematically searched for primary studies that were published in English between July 2002 and July 2012, and which reported on the prevalence of HPV infection in head and neck cancers in European populations. Studies on non-European populations, those not published in English, and those assessing patients co-infected with human immunodeficiency virus were excluded. Eligible studies were combined in a meta-analysis. In addition, the potential statistical association between the head and neck cancers and certain HPV types was investigated.

RESULTS

Thirty-nine publications met the inclusion criteria. The prevalence of HPV of any type in 3,649 patients with head and neck cancers was 40.0% (95% confidence interval, 34.6% to 45.5%), and was highest in tonsillar cancer (66.4%) and lowest in pharyngeal (15.3%) and tongue (25.7%) cancers. There were no statistically significant associations between the HPV types analysed and the geographical setting, type of sample analysed or type of primer used to analyse samples in head and neck cancers.

CONCLUSIONS

The prevalence of HPV infection in European patients with head and neck cancers is high but varies between the different anatomical sites of these malignancies. There appears to be no association between HPV type and geographical setting, type of samples analysed or type of primer used to analyse samples in such cancers.

Development of a quality framework for models of cervical screening and its application to evaluations of the cost-effectiveness of HPV vaccination in developed countries

BACKGROUND

HPV vaccination has now been introduced in most developed countries, but this has occurred in the context of established cervical cancer screening mechanisms which provide population-level protection against the most common HPV-related cancer. Therefore, estimating the cost-effectiveness of HPV vaccination to further reduce HPV-related disease depends in large part on the estimation of the effectiveness of the cervical screening 'background'. The aim of this study was to systematically review and assess methods for simulating cervical screening in decision analytic models used for evaluation of HPV vaccination.

METHODS

Existing quality frameworks for economic models were extended to develop a specific quality framework for models of cervical screening. This involved domains for model structure, parameterisation (data sources) and validation (consistency). A systematic review of economic evaluations of HPV vaccination was then conducted, and assessment of cervical screening model components was then performed via application of the new quality framework.

RESULTS

Generally, models took into account population-level cervical screening participation, but were inconsistent in their approach to modelling abnormal smear management, diagnostic evaluation and treatment of precancerous disease. There was also considerable variability in the accuracy of modelling clinical pathways and the scope of validation performed for screening-related outcomes, with focus directed towards cervical cancer targets. Only a few models comprehensively validated against observed pre-cancerous abnormalities.

CONCLUSION

Models of HPV vaccination in developed countries can be improved by further attention to the 'background' modelling of secondary protection via cervical screening. The quality framework developed for this review can be used to inform future HPV vaccination evaluations, including evaluations of the cost-effectiveness of male vaccination and next generation HPV vaccines, and to assess models used to evaluate new cervical screening technologies and recommendations.

Predictors of HPV vaccination uptake: a longitudinal study among parents

To assess among parents longitudinal predictors of human papillomavirus (HPV) vaccination uptake for their daughters, random samples of parents were identified via municipal services and sent baseline questionnaires in June 2009 and follow-up questionnaires in November 2011 after their uptake decision. Hierarchical logistic regression analysis was used to assess whether demographic characteristics, and affective and social cognitive factors, predicted uptake at follow-up. Response rates of the baseline and follow-up questionnaire were 29.8% (1762/5918) and 74.3% (793/1067), respectively. Uptake was predicted by a later (2011) versus earlier (2010) decision about uptake as HPV vaccination implementation [odds ratio (OR) 2.48; 95% confidence interval (CI) 1.11-5.52], anticipated regret about no uptake (OR 1.43; 95% CI 1.08-1.89) and intention (OR 2.61; 95% CI 1.47-4.61). There was an interaction between ambivalence and attitude (OR 1.68; 95% CI 1.14-2.47); parents with a positive attitude and a high ambivalence toward vaccination were more likely to have their daughter vaccinated than parents with a positive attitude and a low ambivalence. An informed choice about uptake (5/7 correct items) was made by 44%. In conclusion, uptake was predicted by intention, a later (2011) versus earlier (2010) decision and by anticipated regret about no uptake. Decisions regarding new vaccines are difficult to make, we recommend a well-balanced implementation process.

Parental decisional strategies regarding HPV vaccination before media debates: a focus group study

Before the introduction of the human papillomavirus (HPV) vaccine, decisional strategies and factors that could guide HPV vaccination intentions were explored. The authors conducted 4 focus group discussions with 36 parents of children 8-15 years of age. Three groups consisted primarily of Dutch parents and 1 group of only Turkish parents. Discussions followed a semi-structured question route. Results showed that some parents used an approach of systematically seeking information as a way to prepare a decision, whereas others merely relied on trust in the message source. In general, parents believed that it was important to protect their child against negative outcomes that could result from vaccinating or not, and they felt that it is their responsibility to decide about uptake. Perceived susceptibility, vaccine effectiveness, and possibility of serious side effects were most important in the HPV vaccination decision-making process. In conclusion, parents perceived a lack of information and felt insecure about the vaccine's safety and effectiveness. This may result in ambivalent feelings toward HPV vaccination, which, in turn, may lead to postponing decisions about uptake. To facilitate informed decision making, which requires central processing, personally relevant messages about the knowns and unknowns regarding the effects of HPV vaccination should be provided.

Modeling preventative strategies against human papillomavirus-related disease in developed countries

Over the last 5 years, prophylactic vaccination against human papillomavirus (HPV) in pre-adolescent females has been introduced in most developed countries, supported by modeled evaluations that have almost universally found vaccination of pre-adolescent females to be cost-effective. Studies to date suggest that vaccination of pre-adolescent males may also be cost-effective at a cost per vaccinated individual of ~US$400-500 if vaccination coverage in females cannot be increased above ~50%; but if it is possible, increasing coverage in females appears to be a better return on investment. Comparative evaluation of the quadrivalent (HPV16,18,6,11) and bivalent (HPV16,18) vaccines centers around the potential trade-off between protection against anogenital warts and vaccine-specific levels of cross-protection against infections not targeted by the vaccines. Future evaluations will also need to consider the cost-effectiveness of a next generation nonavalent vaccine designed to protect against ~90% of cervical cancers. The timing of the effect of vaccination on cervical screening programs will be country-specific and will depend on vaccination catch-up age range and coverage and the age at which screening starts. Initial evaluations suggest that if screening remains unchanged, it will be less cost-effective in vaccinated compared to unvaccinated women but, in the context of current vaccines, will remain an important prevention method. Comprehensive evaluation of new approaches to screening will need to consider the population-level effects of vaccination over time. New screening strategies of particular interest include delaying the start age of screening, increasing the screening interval and switching to primary HPV screening. Future evaluations of screening will also need to focus on the effects of disparities in screening and vaccination uptake, the potential effects of vaccination on screening participation, and the effects of imperfect compliance with screening recommendations. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.

Long-term impact of human papillomavirus vaccination on infection rates, cervical abnormalities, and cancer incidence

BACKGROUND

Vaccination against human papillomavirus (HPV) types 16/18 is being implemented in many countries. There may be indirect benefit of HPV vaccination to nonvaccinated women, who may experience a reduced risk of infection with vaccine-preventable types (herd immunity). We attempt to disentangle the direct and indirect effects of HPV vaccination, while accounting for 14 oncogenic HPV types in a dynamic modeling framework.

METHODS

On the basis of vaccine uptake among preadolescent girls in the Netherlands, we calculated how heterosexual transmission of HPV-16/18 is expected to change as a result of vaccination, and used these predictions in an individual-based simulation model of cervical carcinogenesis that considers 14 high-risk HPV types. Models were parameterized to match prevaccine data on type-specific HPV infection and cervical disease.

RESULTS

At 50% vaccine coverage, the estimated lifetime infection risk in nonvaccinated women dropped from 0.46 (95% credible interval = 0.35-0.54) to 0.37 (0.26-0.46) for HPV-16, and from 0.40 (0.32-0.46) to 0.31 (0.22-0.36) [corrected] for HPV-18. For the whole population, we calculated an eventual 47% reduction in cervical cancer incidence, with 1 in 4 cases prevented among nonvaccinated women. The number of indirectly averted cancer cases was highest with vaccine coverage between 50% and 70%, approximating 70 cases per 100,000 women born from 2010 onward.

CONCLUSIONS

HPV-16/18 vaccination of preadolescent girls will markedly lower infection rates among nonvaccinated women. Reduced transmission of vaccine-preventable HPV becomes a prominent aspect of cervical cancer control, especially in populations with moderate vaccine coverage.

Economic evaluation of human papilloma virus vaccination in the European Union: a critical review

The human papilloma virus (HPV) vaccine is a new and expensive vaccine potentially effective in the prevention of a cancer. We reviewed the economic evaluations (EEs) on the vaccine in the EU to assess their potential contribution to public decision-making in a fairly homogeneous setting where HPV vaccination has been widely adopted. A literature search on PubMed selected EEs on HPV vaccines in the EU for the period 2007-2010 using the terms "HPV vaccines" and "Costs and cost analysis." Fifteen articles were eventually selected. All studies were based on modelling techniques, either "cohort" or "dynamic transmission": three were cost utility, three cost-effectiveness, and the remainder included both. The ten studies explicitly assessing one of the two vaccines were all sponsored by their manufacturer, while the five studies unrelated to the vaccine type were funded by public agencies. Apart from two studies, utility estimates were always obtained from three US sources. Direct costs were always vaccination, diagnosis and treatment of related pathologies. Incremental cost-effectiveness ratio (ICER) results were less favourable when life years gained were valued rather than quality-adjusted life years, genital warts were excluded, and booster doses and extension of vaccination to men were included in the base-case analysis. All but one of the sponsored EEs recommend in favour of the vaccination strategy, which is dominant in one English study. The ICER results were very sensitive to discount rates, followed by duration of protection and vaccine price. At such an early stage, when the vaccines' efficacy have been demonstrated by well-designed studies, it is not possible (and not even reasonable) to wait for several years to measure their effectiveness; public decision-makers might benefit more from EEs designed to indicate sustainable prices using realistic estimates of crucial variables like coverage rates, rather than referring to a large number of assumptions in order to show acceptable cost-effectiveness.

The paradox of HPV vaccines: how to reach sexually inexperienced women for protection against a sexually transmitted infection

PURPOSE

The current study examined the impact of a human papillomavirus (HPV) vaccine message tailored for sexually inexperienced women.

METHODS

We included 193 young women, aged 17 to 26, attending university, who completed an on-line questionnaire. The participants were randomly assigned to three conditions that manipulated the type of information they received on HPV and the vaccine: control (minimal information, sexual transmission information omitted), detailed (emphasized sexual transmission of HPV), or tailored (the same as detailed, but also emphasized the benefit to sexually inexperienced women).

RESULTS

Women with no sexual experience intended to receive an HPV vaccine more in the tailored condition than the detailed condition (q = 3.46; p < .05) and the control condition (q = 5.11; p < .01). There was no difference between the detailed condition compared with the control condition (q = 1.45; p = NS).

CONCLUSION

This study found that a message tailored for sexually inexperienced women resulted in higher intentions to receive the HPV vaccine compared with messages that were not tailored. When providing information about HPV vaccines to sexually inexperienced patients, it may be particularly important to emphasize that HPV vaccines are most efficacious if received before the onset of sexual activity. The results suggest that this is more effective in increasing sexually inexperienced women's interest in the vaccine than avoiding information about sexual transmission altogether.

Cervix smear abnormalities: linking pathology data in female twins, their mothers and sisters

Mass screening for cervical cancer precursors has decreased the incidence of cervical cancer in several countries, including the Netherlands. Persistent infections of certain types of human papillomavirus are strongly associated with the development of cervical cancer. A number of factors may affect the liability to infection and subsequent progression to cervical intraepithelial neoplasia and cancer. This paper examines whether genetic factors are involved in explaining individual differences in liability. Data of 3178 women registered with the Netherlands Twin Register were successfully linked to the nationwide Dutch Pathology database that contains all results of mass screening for cervical cancer. The data from mono- and dizygotic twins and their female relatives were used to disentangle the influence of heritable and environmental factors on cervix smear abnormalities. Results showed that differences in cervix smear results clustered within families and resemblance was stronger in monozygotic twins (correlation 0.37, 95% confidence interval: 0.12-0.58) compared with other first-degree relatives (correlation 0.14, 95% confidence interval: -0.01-0.29). The familial clustering for an abnormal cervix smear is due to shared genetic factors that explain 37% of the variance in liability. The largest proportion of the variation in cervical smear abnormalities is due to unique environmental factors.

Understanding differences in predictions of HPV vaccine effectiveness: A comparative model-based analysis

Mathematical models of HPV vaccine effectiveness and cost-effectiveness have produced conflicting results. The aim of this study was to use mathematical models to compare and isolate the impact of the assumptions most commonly made when modeling the effectiveness of HPV vaccines. Our results clearly show that differences in how we model natural immunity, herd immunity, partnership duration, HPV types, and waning of vaccine protection lead to important differences in the predicted effectiveness of HPV vaccines. These results are important and useful to assist modelers/health economists in choosing the appropriate level of complexity to include in their models, provide epidemiologists with insight on key data necessary to increase the robustness of model predictions, and help decision makers better understand the reasons underlying conflicting results from HPV models.

A cost-utility analysis of cervical cancer vaccination in preadolescent Canadian females

Background

Despite the fact that approximately 70% of Canadian women undergo cervical cancer screening at least once every 3 years, approximately 1,300 women were diagnosed with cervical cancer and approximately 380 died from it in 2008. This study estimates the effectiveness and cost-effectiveness of vaccinating 12-year old Canadian females with an AS04-adjuvanted cervical cancer vaccine. The indirect effect of vaccination, via herd immunity, is also estimated.

Methods

A 12-health-state 1-year-cycle Markov model was developed to estimate lifetime HPV related events for a cohort of 12-year old females. Annual transition probabilities between health-states were derived from published literature and Canadian population statistics. The model was calibrated using Canadian cancer statistics. From a healthcare perspective, the cost-effectiveness of introducing a vaccine with efficacy against HPV-16/18 and evidence of cross-protection against other oncogenic HPV types was evaluated in a population undergoing current screening practices. The base-case analysis included 70% screening coverage, 75% vaccination coverage, $135/dose for vaccine, and 3% discount rate on future costs and health effects. Conservative herd immunity effects were taken into account by estimated HPV incidence using a mathematical model parameterized by reported age-stratified sexual mixing data. Sensitivity analyses were performed to address parameter uncertainties.

Results

Vaccinating 12-year old females (n = 100,000) was estimated to prevent between 390-633 undiscounted cervical cancer cases (reduction of 47%-77%) and 168-275 undiscounted deaths (48%-78%) over their lifetime, depending on whether or not herd immunity and cross-protection against other oncogenic HPV types were included. Vaccination was estimated to cost $18,672-$31,687 per QALY-gained, the lower range representing inclusion of cross-protective efficacy and herd immunity. The cost per QALY-gained was most sensitive to duration of vaccine protection, discount rate, and the correlation between probability of screening and probability of vaccination.

Conclusion

In the context of current screening patterns, vaccination of 12-year old Canadian females with an ASO4-ajuvanted cervical cancer vaccine is estimated to significantly reduce cervical cancer and mortality, and is a cost-effective option. However, the economic attractiveness of vaccination is impacted by the vaccine's duration of protection and the discount rate used in the analysis.

A cost-utility analysis of adding a bivalent or quadrivalent HPV vaccine to the Irish cervical screening programme

BACKGROUND

Cervical cancer is a leading cause of death worldwide, and in Ireland it is the ninth most commonly diagnosed cancer in women. Almost 100% of these cancers are caused by human papillomavirus (HPV) infection. Two newly developed vaccines against HPV infection have become available. This study is a cost-utility analysis of the HPV vaccine in Ireland, and it compares the cost-effectiveness profiles of the two vaccines.

METHODS

A cost-utility analysis of the HPV vaccine in Ireland was performed using a Markov model. A cohort of screened and vaccinated women was compared with an unvaccinated screened cohort, and both cohorts were followed over their lifetimes. The model looked at uptake of services related to HPV disease in both cohorts. Outcomes were measured in quality adjusted life years (QALYs). Extensive sensitivity analysis was done.

RESULTS

For the base case analysis, the model showed that the incremental cost-effectiveness ratio (ICER) for quadrivalent HPV vaccination would be 25,349 euros/QALY and 30,460 euros/QALY for the bivalent vaccine. The ICER for the quadrivalent vaccine ranged from 2877 euros to 36,548 euros, and for the bivalent from 3399 euros to 45,237 euros. At current prices, the bivalent vaccine would need to be 22% cheaper than the quadrivalent vaccine in order to have equivalent cost effectiveness.

CONCLUSION

HPV vaccination has the potential to be very cost effective in Ireland. The quadrivalent vaccine is more cost effective than the bivalent vaccine.

Cost effectiveness analysis of including boys in a human papillomavirus vaccination programme in the United States

OBJECTIVE

To assess the cost effectiveness of including preadolescent boys in a routine human papillomavirus (HPV) vaccination programme for preadolescent girls.

DESIGN

Cost effectiveness analysis from the societal perspective.

SETTING

United States.

POPULATION

Girls and boys aged 12 years.

INTERVENTIONS

HPV vaccination of girls alone and of girls and boys in the context of screening for cervical cancer. Main outcome measure Incremental cost effectiveness ratios, expressed as cost per quality adjusted life year (QALY) gained.

RESULTS

With 75% vaccination coverage and an assumption of complete, lifelong vaccine efficacy, routine HPV vaccination of 12 year old girls was consistently less than $50,000 per QALY gained compared with screening alone. Including preadolescent boys in a routine vaccination programme for preadolescent girls resulted in higher costs and benefits and generally had cost effectiveness ratios that exceeded $100,000 per QALY across a range of HPV related outcomes, scenarios for cervical cancer screening, and assumptions of vaccine efficacy and duration. Vaccinating both girls and boys fell below a willingness to pay threshold of $100,000 per QALY only under scenarios of high, lifelong vaccine efficacy against all HPV related diseases (including other non-cervical cancers and genital warts), or scenarios of lower efficacy with lower coverage or lower vaccine costs.

CONCLUSIONS

Given currently available information, including boys in an HPV vaccination programme generally exceeds conventional thresholds of good value for money, even under favourable conditions of vaccine protection and health benefits. Uncertainty still exists in many areas that can either strengthen or attenuate our findings. As new information emerges, assumptions and analyses will need to be iteratively revised to continue to inform policies for HPV vaccination.

Cost-effectiveness of human papillomavirus vaccination in Belgium: do not forget about cervical cancer screening

OBJECTIVES

The cost-effectiveness of adding a human papillomavirus (HPV) vaccination program in 12-year-old females to the recommended cervical cancer screening in Belgium is examined. Moreover, the health and economic consequences of a potential decline in screening uptake after initiation of a HPV vaccination program are investigated.

METHODS

A static Markov model is developed to estimate the direct effect of vaccination on precancerous lesions and cervical cancers.

RESULTS

Vaccination is estimated to avoid 20 percent of the cervical cancers occurring in a 12-year-old girls' cohort and to cost 32,665 euro per quality-adjusted life-year (QALY) gained (95 percent credibility interval [CrI]: 17,447 euro to 68,078 euro), assuming a booster injection after 10 years, a limited duration of protection and discounting costs and effects at 3 percent and 1.5 percent, respectively. Assuming lifelong protection, HPV vaccination is estimated to cost 14,382 euro (95 percent CrI: 9,238 euro to 25,644 euro) per QALY gained, while avoiding 50 percent of the cervical cancer cases. In the base-case, a 10 percent reduction in screening compliance after vaccination obliterates the effect of vaccination on cervical cancer cases avoided, whereas further declines in the level of screening compliance even turned out to be detrimental for the cohort's health, inducing a mean loss in QALYs and life-year gained compared with the situation prevaccination.

CONCLUSIONS

An HPV vaccination program should only be considered if the level of screening after vaccination can be maintained.

Economic evaluations of massive HPV vaccination: within-study and between study variations in incremental cost per QALY gained

OBJECTIVE

We describe the heterogeneity of the estimates of the incremental cost per quality-adjusted year of life (QALY) within and between cost-utility studies of the human papillomavirus (HPV) vaccine.

METHOD

We searched for articles in English published in peer-reviewed journals that perform cost-utility analyses to evaluate the addition of HPV vaccine to 12-year-old girls to existing cervical cancer screening practices. Fifteen studies were selected according to our inclusion and exclusion criteria.

RESULTS

There are large within-study variations in estimates of the cost per QALY gained. The most influential source of uncertainty is the duration of the vaccine protection. Between-study variations are mainly due to three causes: methodological differences, assumptions, and local conditions in the application area. We find large variations between studies for a given country.

DISCUSSION

Economic evaluation models are increasingly sophisticated, but scientific treatment of epidemiological and market uncertainty does not compensate for the lack of basic information.

CONCLUSIONS

The large disparities in cost per QALY estimates of massive vaccination programs around the world may be attributed to several critical sources (unavoidable and avoidable) of uncertainty. An asset of economic evaluation is the ability to highlight the areas of research that could be undertaken to reduce uncertainty.

HPV16/18 vaccination to prevent cervical cancer in The Netherlands: model-based cost-effectiveness

We evaluated the cost-effectiveness of HPV16/18 vaccination for girls aged 12 years in The Netherlands in addition to cervical cancer screening. For this purpose, we developed a simulation model that describes the relation between each of the high-risk human papillomavirus (hrHPV) types and cervical disease, allowing the occurrence of multiple type-specific infections. Model parameters were derived from Dutch cohort studies, including a large population-based screening trial, and from the national cervical cancer registry. The model satisfactorily reproduced Dutch data on HPV infection and the presence of cervical lesions. For our base-case scenario in which 85% of the girls aged 12 years were vaccinated against types 16/18 (95% efficacy, lifelong protection), the model predicted a decrease of 60% in the number of cervical cancer cases and cervical cancer deaths indicating that substantial health benefits can be achieved. Health savings were robust against changes in the vaccine efficacy (varied from 85% to 98%) but savings showed a substantial reduction when the efficacy started waning 10 years after vaccination. The discounted costs per quality-adjusted life year (QALY) were euro 19,500/QALY (range euro 11,000 to euro 25,000/QALY) and lied near the cost-effectiveness threshold of euro 20,000/QALY used in The Netherlands. The simulations further showed that vaccination cannot replace screening because vaccination without screening was less effective than screening in preventing cancer in women over 40 years of age. In conclusion, our model results support the implementation of HPV16/18 vaccination in young women in addition to cervical cancer screening.

Structural differences among cost-effectiveness models of human papillomavirus vaccines

In this article we compare previously published cost-effectiveness studies of human papillomavirus (HPV) vaccines along a defined subset of key model structural assumptions relating to HPV infection and disease, cervical cancer screening and HPV vaccination. For each structural aspect examined, we summarize assumptions from each study, provide a critical review and discuss the impact upon results. Considerable variation was observed across HPV vaccine cost-effectiveness models in a number of influential assumptions. Holding constant factors for which current data are lacking, the combined impact of assumptions made for the remaining parameters examined would appear to tend toward underestimation of the cost-effectiveness of HPV vaccination within existing studies. However, uncertainty concerning parameters, such as the duration of vaccine protection and acquired immunity following HPV infection, and the relationship between age and HPV virulence, complicates precise estimation of the cost-effectiveness of HPV vaccination and rigorous evaluation of the validity of existing modeling results.

Health and economic implications of HPV vaccination in the United States

BACKGROUND

The cost-effectiveness of prophylactic vaccination against human papillomavirus types 16 (HPV-16) and 18 (HPV-18) is an important consideration for guidelines for immunization in the United States.

METHODS

We synthesized epidemiologic and demographic data using models of HPV-16 and HPV-18 transmission and cervical carcinogenesis to compare the health and economic outcomes of vaccinating preadolescent girls (at 12 years of age) and vaccinating older girls and women in catch-up programs (to 18, 21, or 26 years of age). We examined the health benefits of averting other HPV-16-related and HPV-18-related cancers, the prevention of HPV-6-related and HPV-11-related genital warts and juvenile-onset recurrent respiratory papillomatosis by means of the quadrivalent vaccine, the duration of immunity, and future screening practices.

RESULTS

On the assumption that the vaccine provided lifelong immunity, the cost-effectiveness ratio of vaccination of 12-year-old girls was $43,600 per quality-adjusted life-year (QALY) gained, as compared with the current screening practice. Under baseline assumptions, the cost-effectiveness ratio for extending a temporary catch-up program for girls to 18 years of age was $97,300 per QALY; the cost of extending vaccination of girls and women to the age of 21 years was $120,400 per QALY, and the cost for extension to the age of 26 years was $152,700 per QALY. The results were sensitive to the duration of vaccine-induced immunity; if immunity waned after 10 years, the cost of vaccination of preadolescent girls exceeded $140,000 per QALY, and catch-up strategies were less cost-effective than screening alone. The cost-effectiveness ratios for vaccination strategies were more favorable if the benefits of averting other health conditions were included or if screening was delayed and performed at less frequent intervals and with more sensitive tests; they were less favorable if vaccinated girls were preferentially screened more frequently in adulthood.

CONCLUSIONS

The cost-effectiveness of HPV vaccination will depend on the duration of vaccine immunity and will be optimized by achieving high coverage in preadolescent girls, targeting initial catch-up efforts to women up to 18 or 21 years of age, and revising screening policies.

Modeling cervical cancer prevention in developed countries

Cytology-based screening has reduced cervical cancer mortality in countries able to implement, sustain and financially support organized programs that achieve broad coverage. These ongoing secondary prevention efforts considerably complicate the question of whether vaccination against human papillomavirus (HPV) types 16 and 18 should be introduced. Policy questions focus primarily on the target ages of vaccination, appropriate ages for a temporary "catch-up" program, possible revisions in screening policies to optimize synergies with vaccination, including the increased used of HPV DNA testing, and the inclusion of boys in the vaccination program. Decision-analytic models are increasingly being developed to simulate disease burden and interventions in different settings in order to evaluate the benefits and cost-effectiveness of primary and secondary interventions for informed decision-making. This article is a focused review on existing mathematical models that have been used to evaluate HPV vaccination in the context of developed countries with existing screening programs. Despite variations in model assumptions and uncertainty in existing data, pre-adolescent vaccination of girls has been consistently found to be attractive in the context of current screening practices, provided there is complete and lifelong vaccine protection and widespread vaccination coverage. Questions related to catch-up vaccination programs, potential benefits of other non-cervical cancer outcomes and inclusion of boys are subject to far more uncertainty, and results from these analyses have reached conflicting conclusions. Most analyses find that some catch-up vaccination is warranted but becomes increasingly unattractive as the catch-up age is extended, and vaccination of boys is unlikely to be cost-effective if reasonable levels of coverage are achieved in girls or coverage among girls can be improved. The objective of this review is to highlight points of consensus and qualitative themes, to discuss the areas of divergent findings, and to provide insight into critical decisions related to cervical cancer prevention.

Human papillomavirus types 16 and 18 vaccine (recombinant, AS04 adjuvanted, adsorbed) [Cervarix]

Cervarix is a prophylactic vaccine comprised of a mixture of virus-like particles derived from the L1 capsid proteins of human papillomavirus (HPV) types 16 and 18 formulated with the AS04 adjuvant system. It is administered by intramuscular injection as a three-dose vaccine regimen at 0, 1 and 6 months. The vaccine is indicated for the prevention of high-grade cervical intraepithelial neoplasia (CIN 2 and CIN 3) and cervical cancer causally related to HPV types 16 and 18. In randomized, double-blind, phase II or III trials in >19,000 women aged 15-25 years, the HPV 16/18 vaccine showed high efficacy in preventing CIN 2+ associated with HPV 16/18. Cross-protection against new incident or 6-month persistent HPV 45 or HPV 31 infection was also evident. Phase II follow-up was for at least 5.5 years, and the phase III interim analysis was at approximately 15 months after the first vaccine dose. In a bridging study, in adolescent girls aged 10-14 years, the HPV 16/18 vaccine induced twice the already high antibody titres as it did in young women (aged 15-25 years). The immune response in older women (aged 26-55 years) at 24 months in another study was >or= 8-fold higher than antibody levels reported in younger age groups. Anti-HPV 16/18 antibody responses were greater with an AS04-adjuvanted HPV 16/18 vaccine than with an aluminium salt-adjuvanted formulation. The HPV 16/18 vaccine was generally well tolerated and injection-site reactions were the most common vaccine-related adverse events reported.

Evaluating human papillomavirus vaccination programs in Canada: should provincial healthcare pay for voluntary adult vaccination?

Background

Recently, provincial health programs in Canada and elsewhere have begun rolling out vaccination against human papillomavirus for girls aged 9–13. While vaccination is voluntary, the cost of vaccination is waived, to encourage parents to have their daughters vaccinated. Adult women who are eligible for the vaccine may still receive it, but at a cost of approximately CAN$400. Given the high efficacy and immunogenicity of the vaccine, the possibility of eradicating targeted types of the virus may be feasible, assuming the vaccination programs are undertaken strategically.

Methods

We develop a mathematical model to describe the epidemiology of vaccination against human papillomavirus, accounting for a widespread childhood vaccination program that may be supplemented by voluntary adult vaccination. A stability analysis is performed to determine the stability of the disease-free equilibrium. The critical vaccine efficacy and immunogenicity thresholds are derived, and the minimum level of adult vaccination required for eradication of targeted types is determined.

Results

We demonstrate that eradication of targeted types is indeed feasible, although the burden of coverage for a childhood-only vaccination program may be high. However, if a small, but non-negligible, proportion of eligible adults can be vaccinated, then the possibility of eradication of targeted types becomes much more favourable. We provide a threshold for eradication in general communities and illustrate the results with numerical simulations. We also investigate the effects of suboptimal efficacy and immunogenicity and show that there is a critical efficacy below which eradication of targeted types is not possible. If eradication is possible, then there is a critical immunogenicity such that even 100% childhood vaccination will not eradicate the targeted types of the virus and must be supplemented with voluntary adult vaccination. However, the level of adult vaccination coverage required is modest and may be achieved simply by removing the cost burden to vaccination.

Conclusion

We recommend that provincial healthcare programs should pay for voluntary adult vaccination for women aged 14–26. However, it should be noted that our model results are preliminary, in that we have made a number of simplifying assumptions, including a lack of age-dependency in sexual partner rates, a lack of sexual activity outside of the vaccine age-range among females and a uniform age of sexual debut; thus, further work is desired to enhance the external generalisability of our results.