Estimating the long-term impact of a prophylactic human papillomavirus 16/18 vaccine on the burden of cervical cancer in the UK

Cost-Effectiveness of Human Papillomavirus Vaccination in the UK: Two Versus Single-Dose of Nonavalent HPV Vaccination

INTRODUCTION

The UK implemented a single-dose HPV vaccination policy in September 2023, aiming for sustained protection, better vaccine coverage, and reduced healthcare costs. This research assesses the cost-effectiveness of both one-dose and two-dose schedules from a healthcare perspective.

METHODS

Using an age-structured dynamic model, the study analyzed long-term health and economic outcomes of these two different vaccination approaches. It focused on the effects of vaccinating 12- to 13-year-olds with the 9-valent HPV vaccine in either single-dose or two-dose regimens from 2023 to 2093. The analysis, conducted in 2023-2024, explored different immunity durations (10, 30 years, or lifetime) and efficacy levels for the single-dose strategy.

RESULTS

The study indicated that in the UK, vaccinating 12- to 13-year-olds with a two-dose regimen is not considered cost-effective compared to the single-dose option, assumed to be 90% as effective for 10 years. The incremental cost-effectiveness ratios for two doses ranged from £230,903 to £1,082,916 per quality-adjusted life year (QALY), significantly exceeding the UK's £20,000/QALY willingness-to-pay threshold. Over 70 years, a switch from a two-dose to a single-dose vaccination schedule could potentially lead to savings of over £1,073 million in the healthcare system. Furthermore, the single-dose regimen was cost-effective compared to no vaccination, with an incremental cost-effectiveness ratio below £2,040/QALY.

CONCLUSIONS

The study affirms the cost-effectiveness of the UK's single-dose HPV vaccine, in sync with its September 2023 policy shift. The shift not only provides financial benefits but also simplifies vaccine administration, strategically reducing HPV's epidemiological and economic impacts.

Rapid evaluation of service innovations in health and social care: key considerations

Funding

This project was funded by the National Institute for Health and Care Research (NIHR) Health and Social Care Delivery Research programme (RSET: 16/138/17; BRACE: 16/138/31).

Eradicating cervical cancer: Lessons learned from Rwanda and Australia

Both Rwanda and Australia have made significant strides to eradicate cervical cancer. To understand the successes in Rwanda and Australia, a comparative policy analysis was conducted based on key informant interviews and a review of peer-reviewed literature and policy briefs. Notable findings were identified that offer lessons for countries across the income spectrum. To address cervical cancer, low- and middle-income countries can leverage foreign aid, international collaboration, and strong political advocacy, as Rwanda did. High-income countries can invest in translational research that builds capacity from basic science research to implementation of novel and impactful health products and services, as Australia did. All countries can consider rolling out HPV vaccination by targeting the social and/or physical environment (e.g., a school-based vaccination program, as both Rwanda and Australia did). Cervical cancer is preventable, and eradication is within reach for countries across the income spectrum around the world. Cervical cancer screening programs are needed to minimize the incidence of and mortality from cervical cancer in the short term, and HPV vaccination programs are the best strategy to eradicate cervical cancer in the long term.

Assessing the cost-effectiveness of HPV vaccination strategies for adolescent girls and boys in the UK

BACKGROUND

Human papillomavirus (HPV) is the most widespread sexually transmitted infection worldwide. It causes several health consequences, in particular accounting for the majority of cervical cancer cases in women. In the United Kingdom, a vaccination campaign targeting 12-year-old girls started in 2008; this campaign has been successful, with high uptake and reduced HPV prevalence observed in vaccinated cohorts. Recently, attention has focused on vaccinating both sexes, due to HPV-related diseases in males (particularly for high-risk men who have sex with men) and an equity argument over equalising levels of protection.

METHODS

We constructed an epidemiological model for HPV transmission in the UK, accounting for nine of the most common HPV strains. We complemented this with an economic model to determine the likely health outcomes (healthcare costs and quality-adjusted life years) for individuals from the epidemiological model. We then tested vaccination with the three HPV vaccines currently available, vaccinating either girls alone or both sexes. For each strategy we calculated the threshold price per vaccine dose, i.e. the maximum amount paid for the added health benefits of vaccination to be worth the cost of each vaccine dose. We calculated results at 3.5% discounting, and also 1.5%, to consider the long-term health effects of HPV infection.

RESULTS

At 3.5% discounting, continuing to vaccinate girls remains highly cost-effective compared to halting vaccination, with threshold dose prices of £56-£108. Vaccination of girls and boys is less cost-effective (£25-£53). Compared to vaccinating girls only, adding boys to the programme is not cost-effective, with negative threshold prices (-£6 to -£3) due to the costs of administration. All threshold prices increase when using 1.5% discounting, and adding boys becomes cost-effective (£36-£47). These results are contingent on the UK's high vaccine uptake; for lower uptake rates, adding boys (at the same uptake rate) becomes more cost effective.

CONCLUSIONS

Vaccinating girls is extremely cost-effective compared with no vaccination, vaccinating both sexes is less so. Adding boys to an already successful girls-only programme has a low cost-effectiveness, as males have high protection through herd immunity. If future health effects are weighted more heavily, threshold prices increase and vaccination becomes cost-effective.

Impact of HPV vaccination with Gardasil® in Switzerland

BACKGROUND

Gardasil®, a quadrivalent vaccine targeting low-risk (6, 11) and high-risk (16, 18) human papillomaviruses (HPV), has been offered to 11-14 year-old schoolgirls in Switzerland since 2008. To evaluate its success and its potential impact on cervical cancer screening, HPV genotypes were examined in 18-year-old girls five years later (sub-study 1) and in outpatients participating to cervical cancer screening before and after vaccine implementation (sub-study 2).

METHODS

For sub-study 1, 3726 females aged 18 in 2013 were invited to fill a questionnaire on personal demographics and HPV risk factors and to provide a self-collected cervicovaginal sample for HPV genotyping and Chlamydia trachomatis PCR. Personal data were evaluated by univariable and multivariable statistics. In sub-study 2, the proportion of the vaccine-type HPV among anogenital HPV was examined with archived genotyping data of 8039 outpatients participating to cervical cancer screening from 1999 till 2015. The yearly evolution of this proportion was evaluated by segmented logistic regression.

RESULTS

690 (18.5%) women participated to sub-study 1 and 327 (8.8%) provided a self-collected sample. Prevalence of Chlamydia trachomatis (4.6%) and demographics confirmed that the subjects were representative of sexually-active Swiss young women. Vaccine (five-year coverage: 77.5%) was preferentially accepted by contraceptive-pill users (P = 0.001) and samples were mainly provided by sexually-active subjects (P < 0.001). The proportion (4%) of the vaccine-type HPV in this population was lower than in sub-study 2 outpatients (n = 849, <26 years old) in the pre-vaccine era (25.7%). The proportion of the high-risk vaccine-type HPV decreased significantly (59%, P = 0.0048) in the outpatients during the post-vaccine era, yet this decrease was restricted to those aged less than 26 years (n = 673, P < 0.0001).

CONCLUSIONS

The low proportion of vaccine-type HPV in 18-year-old females and its rapid decrease in young women participating to cervical cancer screening extend the success of HPV vaccination to Switzerland. Our data suggest that cervical cancer screening is now entering a stage of reduced proportion of HPV16 and/or 18 in samples reported positive by cytology. In view of the high likelihood of reduced clinical specificity of cytology, primary screening modalities involving HPV testing and cytology should now be re-evaluated in Switzerland.

Cost-effectiveness of human papillomavirus vaccination in Germany

BACKGROUND

The aim of this study was to assess the cost-effectiveness of human papillomavirus (HPV) vaccination in addition to the current cervical cancer screening programme in Germany using a dynamic transmission model.

METHODS

Based on a mathematical model simulating the transmission dynamics and the natural history of HPV infection and associated diseases (cervical intraepithelial neoplasia, cervical cancer, and genital warts), we estimated the epidemiological and economic consequences of HPV vaccination with both the quadrivalent and bivalent vaccines. In our base case analysis, we assessed the cost-effectiveness of vaccinating 12-year-old girls with a 3-dose schedule. In sensitivity analysis, we also evaluated the use of a 2-dose schedule and assessed the impact of vaccinating boys.

RESULTS

From a health care payer perspective, incremental cost-effectiveness ratios (ICERs) of a 3-dose schedule were €34,249 per quality-adjusted life year (QALY) for the bivalent and €14,711 per QALY for the quadrivalent vaccine. Inclusion of indirect costs decreased ICERs by up to 40%. When adopting a health care payer perspective, ICERs of a 2-dose approach decreased to €19,450 per QALY for the bivalent and to €3645 per QALY for the quadrivalent vaccine. From a societal perspective, a 2-dose approach using the quadrivalent vaccine was a cost-saving strategy while using the bivalent vaccine resulted in an ICER of €13,248 per QALY. Irrespective of the perspective adopted, additional vaccination of boys resulted in ICERs exceeding €50,000 per QALY, except for scenarios with low coverage (20%) in girls.

CONCLUSIONS

Our model results suggest that routine HPV vaccination of 12-year-old girls with three doses is likely to be cost-effective in Germany. Due to the additional impact on genital warts, the quadrivalent vaccine appeared to be more cost-effective than the bivalent vaccine. A 2-dose schedule of the quadrivalent vaccine might even lead to cost savings when adopting a societal perspective. The cost-effectiveness of additional vaccination of boys was highly dependent on the coverage in girls.

Validation and calibration of structural models that combine information from multiple sources

INTRODUCTION

Mathematical models that attempt to capture structural relationships between their components and combine information from multiple sources are increasingly used in medicine. Areas covered: We provide an overview of methods for model validation and calibration and survey studies comparing alternative approaches. Expert commentary: Model validation entails a confrontation of models with data, background knowledge, and other models, and can inform judgments about model credibility. Calibration involves selecting parameter values to improve the agreement of model outputs with data. When the goal of modeling is quantitative inference on the effects of interventions or forecasting, calibration can be viewed as estimation. This view clarifies issues related to parameter identifiability and facilitates formal model validation and the examination of consistency among different sources of information. In contrast, when the goal of modeling is the generation of qualitative insights about the modeled phenomenon, calibration is a rather informal process for selecting inputs that result in model behavior that roughly reproduces select aspects of the modeled phenomenon and cannot be equated to an estimation procedure. Current empirical research on validation and calibration methods consists primarily of methodological appraisals or case-studies of alternative techniques and cannot address the numerous complex and multifaceted methodological decisions that modelers must make. Further research is needed on different approaches for developing and validating complex models that combine evidence from multiple sources.

Human papilloma virus vaccination: Review article and an update

Human papilloma virus (HPV) is sexually transmitted and associated with uterine cervix, vaginal, and vulvar cancers in females, oropharyngeal and anal cancer in both genders, and penile cancer in males. Moreover, genital warts are benign tumors which are HPV-related and can occur in both genders. This is a review of HPV structure, HPV infection transmission, the global impact of HPV and its associated diseases, HPV vaccines and their efficacy and safety, public acceptance of HPV vaccines, the obstacles for its acceptance and strategies to address the barriers. Cervarix (a bivalent vaccine with protection against HPV types 16 and 18) and Gardasil (a quadrivalent vaccine with protection against HPV types 6, 11, 16 and 18) are 2 recommended vaccines. The longest follow up of 9.4 years has shown efficacy and protection of the vaccine against HPV types 16 and 18. The adverse effects have been minimal and the vaccine is considered safe. Numerous studies are conducted to follow the vaccinated individuals to better understand the effect of HPV vaccine on incidence of HPV-related cancers and precancerous lesions.

HPV prevalence and type-distribution in cervical cancer and premalignant lesions of the cervix: A population-based study from Northern Ireland

Assessment of Human papillomavirus (HPV) prevalence and genotype distribution is important for monitoring the impact of prophylactic HPV vaccination. This study aimed to demonstrate the HPV genotypes predominating in pre-malignant and cervical cancers in Northern Ireland (NI) before the vaccination campaign has effect. Formalin fixed paraffin embedded tissue blocks from 2,303 women aged 16-93 years throughout NI were collated between April 2011 and February 2013. HPV DNA was amplified by PCR and HPV genotyping undertaken using the Roche(®) linear array detection kit. In total, 1,241 out of 1,830 eligible samples (68.0%) tested positive for HPV, with the majority of these [1,181/1,830 (64.5%)] having high-risk (HR) HPV infection; 37.4% were positive for HPV-16 (n = 684) and 5.1% for HPV-18 (n = 93). HPV type-specific prevalence was 48.1%, 65.9%, 81.3%, 92.2%, and 64.3% among cervical intraepithelial neoplasias (CIN) Grades I-III, squamous cell carcinomas (SCC) and adenocarcinoma (AC) cases, respectively. Most SCC cases (81.3%) had only one HPV genotype detected and almost a third (32.0%) of all cervical pathologies were HPV negative including 51.9% of CIN I (n = 283), 34.1% CIN II (n = 145), 18.7% of CIN III (n = 146), 7.8% of SCC (n = 5), and 35.7% of AC (n = 5) cases. This study provides important baseline data for monitoring the effect of HPV vaccination in NI and for comparison with other UK regions. The coverage of other HR-HPV genotypes apart from 16 and 18, including HPV-45, 31, 39, and 52, and the potential for cross protection, should be considered when considering future polyvalent vaccines.

The Dynamics of HPV Infection and Cervical Cancer Cells

The development of cervical cells from normal cells infected by human papillomavirus into invasive cancer cells can be modeled using population dynamics of the cells and free virus. The cell populations are separated into four compartments: susceptible cells, infected cells, precancerous cells and cancer cells. The model system of differential equations also has a free virus compartment in the system, which infect normal cells. We analyze the local stability of the equilibrium points of the model and investigate the parameters, which play an important role in the progression toward invasive cancer. By simulation, we investigate the boundary between initial conditions of solutions, which tend to stable equilibrium point, representing controlled infection, and those which tend to unbounded growth of the cancer cell population. Parameters affected by drug treatment are varied, and their effect on the risk of cancer progression is explored.

Mothers' acceptance of human papillomavirus (HPV) vaccination for daughters in a country with a high prevalence of HPV

Cervical cancer is the second most common cancer among women in Argentina and the mortality rate is not declining despite opportunistic screening. Free-of-charge human papillomavirus (HPV) vaccination of 11-year-old girls was introduced in 2011. Parental acceptance of HPV vaccination is considered to be of great importance for HPV vaccine uptake. However, little is known regarding this factor in Argentina. The aim of the present study was to explore maternal HPV vaccination acceptance, willingness to pay for HPV vaccination and correlates of this willingness, awareness of HPV and HPV-associated disease and behaviors and attitudes associated with HPV vaccination acceptance. A total of 180 mothers of girls aged 9-15 years comprised this quantitative, cross-sectional, survey-based study, conducted at two hospitals in the Mendoza Province. Correlates of willingness to pay for HPV vaccination were obtained using multivariable logistic regression models. Maternal HPV vaccination acceptance was 90%, and 60% of mothers were willing to pay for HPV vaccination. Mothers who were gainfully employed and had a higher disposable household income were significantly more willing to pay for HPV vaccination [odds ratio (OR)=2.54, 95% confidence interval (CI) 1.01-6.38; OR=3.28, 95% CI 1.36-7.94, respectively], as were mothers who were aware of cervical cancer prior to the study (OR=3.22, 95% CI 1.02-10.14). Only one in 10 mothers were informed that HPV vaccination does not offer complete protection against cervical cancer. In conclusion, the present study showed high maternal HPV vaccination acceptance, although acceptance decreased when vaccination was not free-of-charge. Continuous public education campaigns are needed to improve knowledge of HPV, HPV vaccines and HPV-associated disease.

Cost-effectiveness of a bivalent human papillomavirus vaccination program in Japan

Background Human papillomavirus (HPV) vaccines and their widespread adoption have the potential to relieve a large part of the burden of cervical cancer morbidity and mortality, particularly in countries that have low screening rates or, like Japan, lack a cohesive universal screening program. An economic evaluation was conducted to assess the cost-effectiveness of introducing a bivalent HPV vaccination program in Japan from a healthcare perspective. Methods: A Markov model of the natural history of HPV infection that incorporates both vaccination and screening was developed for Japan. The modelled intervention, a bivalent HPV vaccine with a 100% lifetime vaccine efficacy and 80% vaccine coverage, given to a cohort of 12-year-old Japanese girls in conjunction with the current screening program, was compared with screening alone in terms of costs and effectiveness. A discount rate of 5% was applied to both costs and utilities where relevant. Results: Vaccination alongside screening compared with screening alone is associated with an incremental cost-effectiveness ratio (ICER) of US$20 315 per quality-adjusted-life-year gained if 80% coverage is assumed. The ICER at 5% coverage with the vaccine plus screening, compared with screening alone, is US$1158. Conclusion: The cost-effectiveness results suggest that the addition of a HPV vaccination program to Japan’s cervical cancer screening program is highly likely to prove a cost-effective way to reduce the burden of cervical cancer, precancerous lesions and HPV16/18-related diseases.

Predictors of having heard about human papillomavirus vaccination: Critical aspects for cervical cancer prevention among Colombian women

OBJECTIVES

To determine whether the probability of having heard about human papillomavirus (HPV) vaccination differs by socio-demographic characteristics among Colombian women; and whether the effect of predictors of having heard about HPV vaccination varies by educational levels and rural/urban area of residence.

METHODS

Data of 53,521 women aged 13-49 years were drawn from the 2010 Colombian National Demographic and Health Survey. Women were asked about aspects of their health and their socio-demographic characteristics. A logistic regression model was used to identify factors associated with having heard about HPV vaccination. Educational level and rural/urban area of residence of the women were tested as modifier effects of predictors.

RESULTS

26.8% of the women had heard about HPV vaccination. The odds of having heard about HPV vaccination were lower among women: in low wealth quintiles, without health insurance, with subsidized health insurance, and those who had children (p<0.001). Although women in older age groups and with better education had higher probabilities of having heard about HPV vaccination, differences in these probabilities by age group were more evident among educated women compared to non-educated ones. Probability gaps between non-educated and highly educated women were wider in the Eastern region. Living in rural areas decreased the probability of having heard about HPV vaccination, although narrower rural/urban gaps were observed in the Atlantic and Amazon-Orinoquía regions.

CONCLUSIONS

Almost three quarters of the Colombian women had not heard about HPV vaccination, with variations by socio-demographic characteristics. Women in disadvantaged groups were less likely to have heard about HPV vaccination.

Colposcopic management of abnormal cervical cytology and histology

OBJECTIVE

To provide a guideline for managing abnormal cytology results after screening for cervical cancer, to clarify the appropriate algorithms for follow-up after treatment, and to promote the best possible care for women while ensuring efficient use of available resources.

OUTCOMES

Women with abnormal cytology are at risk of developing cervical cancer; appropriate triage and treatment will reduce this risk. This guideline will facilitate implementation of common standards across Canada, moving away from the current trend of individual guidelines in each province and territory.

EVIDENCE

Published literature was retrieved through searches of PubMed or Medline, CINAHL, and The Cochrane Library in October 2008 using appropriate controlled vocabulary (e.g., colposcopy, cervical dysplasia) and key words (e.g., colposcopy management, CIN, AGC, cervical dysplasia, LEEP, LLETZ, HPV testing, cervical dysplasia triage). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to July 2012. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, and national and international medical specialty societies. Expert opinion from published peer-reviewed literature and evidence from clinical trials is summarized. Consensus opinion is outlined when evidence is insufficient.

VALUES

The quality of the evidence is rated using the criteria described by the Canadian Task Force on Preventive Health Care (Table 1).

VALIDATION

This guideline has been reviewed for accuracy from content experts in cytology, pathology, and cervical screening programs. Guideline content was also compared with similar documents from other organizations including the American Society for Colposcopy and Cervical Pathology, the British Society for Colposcopy and Cervical Pathology, and the European Cancer Network.

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.

Human Papillomavirus vaccination acceptability among female university students in South Africa

BACKGROUND

The objectives of this present study were to assess the awareness of cervical cancer and its risk factors among female undergraduates in South Africa, and to determine the their level of acceptability of Human Papillomavirus (HPV) vaccination.

MATERIALS AND METHODS

This cross-sectional study was conducted in March 2013 among 440 full time undergraduate female students.

RESULTS

Of those students who never had sex (n=163), 96 (58.9%) had ever heard of cervical cancer and only 12 students (12.5%) knew that HPV causes cervical cancer. More than a third (35.4%) of the students correctly said that sexual intercourse before age of 18 years is a risk factor for cervical cancer and 55.2% of the students knew about the Pap smear test which is used for screening cervical cancer. The majority (77.3%) were willing to accept HPV vaccination. Results revealed that students who knew about the Pap smear test, and were aware that having multiple sex partners, sexual intercourse before the age of 18 years, smoking and having contracted any STDs are risk factors for cervical cancer were more likely to accept HPV vaccination compared to other groups.

CONCLUSIONS

The general knowledge of South African female university students about cervical cancer is not sufficient but they have positive attitudes toward getting vaccinated with the HPV vaccine.

Uptake of the HPV vaccination programme in England: a cross-sectional survey of young women attending sexual health services

OBJECTIVES

The U.K. human papilloma virus (HPV) vaccination programme requires 80% uptake to have a significant impact on cervical cancer rates. Uptake in the first three years of the programme was 66%. We report the results of a cross-sectional survey of young women attending sexual health services (SHS) in England, reviewing HPV vaccination uptake and prevalence of HPV-related risk factors.

METHODS

An anonymous questionnaire surveyed women aged 13-19 attending 19 hospital-based and 13 community-based SHS across England, March-August 2011. Data were analysed using multiple logistic regression.

RESULTS

2247 questionnaires were completed. Compared with national data, respondents had higher smoking rates (48% vs. 14% of 15 year olds), coitarche under-16 (52% vs. 38%), previous sexually transmitted infections (STIs) (25% vs. 4%) and a higher proportion not in education, employment or training (NEETs) (8% vs. 2% of 16 year olds). Seventy-four per cent had been offered the vaccination, with significantly lower offer rates in London, non-white ethnicities, 17-19 year olds, NEETs, smokers and those with previous STIs (all p<0.05 in multivariate analysis). Sixty-five per cent of those offered, completed, with significantly lower completion rates in London, non-white ethnicities, 17-19 year olds, NEETs, smokers and those with previous STIs (all p<0.05 in multivariate analysis). Overall completion rate was 47%.

CONCLUSIONS

We observed lower vaccination offer and completion rates and higher prevalence of HPV-related risk factors compared with national data. The highest risk individuals were the least likely to have been offered or to have completed the course. This survey highlights an opportunity for primary prevention by routinely offering the HPV vaccine to eligible women attending SHS.

Calibration of complex models through Bayesian evidence synthesis: a demonstration and tutorial

Decision-analytic models must often be informed using data that are only indirectly related to the main model parameters. The authors outline how to implement a Bayesian synthesis of diverse sources of evidence to calibrate the parameters of a complex model. A graphical model is built to represent how observed data are generated from statistical models with unknown parameters and how those parameters are related to quantities of interest for decision making. This forms the basis of an algorithm to estimate a posterior probability distribution, which represents the updated state of evidence for all unknowns given all data and prior beliefs. This process calibrates the quantities of interest against data and, at the same time, propagates all parameter uncertainties to the results used for decision making. To illustrate these methods, the authors demonstrate how a previously developed Markov model for the progression of human papillomavirus (HPV-16) infection was rebuilt in a Bayesian framework. Transition probabilities between states of disease severity are inferred indirectly from cross-sectional observations of prevalence of HPV-16 and HPV-16-related disease by age, cervical cancer incidence, and other published information. Previously, a discrete collection of plausible scenarios was identified but with no further indication of which of these are more plausible. Instead, the authors derive a Bayesian posterior distribution, in which scenarios are implicitly weighted according to how well they are supported by the data. In particular, we emphasize the appropriate choice of prior distributions and checking and comparison of fitted models.

Estimates of the timing of reductions in genital warts and high grade cervical intraepithelial neoplasia after onset of human papillomavirus (HPV) vaccination in the United States

BACKGROUND

The objective of this study was to estimate the number of years after onset of a quadrivalent HPV vaccination program before notable reductions in genital warts and cervical intraepithelial neoplasia (CIN) will occur in teenagers and young adults in the United States.

METHODS

We applied a previously published model of HPV vaccination in the United States and focused on the timing of reductions in genital warts among both sexes and reductions in CIN 2/3 among females. Using different coverage scenarios, the lowest being consistent with current 3-dose coverage in the United States, we estimated the number of years before reductions of 10%, 25%, and 50% would be observed after onset of an HPV vaccination program for ages 12-26 years.

RESULTS

The model suggested female-only HPV vaccination in the intermediate coverage scenario will result in a 10% reduction in genital warts within 2-4 years for females aged 15-19 years and a 10% reduction in CIN 2/3 among females aged 20-29 years within 7-11 years. Coverage had a major impact on when reductions would be observed. For example, in the higher coverage scenario a 25% reduction in CIN2/3 would be observed with 8 years compared with 15 years in the lower coverage scenario.

CONCLUSIONS

Our model provides estimates of the potential timing and magnitude of the impact of HPV vaccination on genital warts and CIN 2/3 at the population level in the United States. Notable, population-level impacts of HPV vaccination on genital warts and CIN 2/3 can occur within a few years after onset of vaccination, particularly among younger age groups. Our results are generally consistent with early reports of declines in genital warts among youth.

Female human papillomavirus (HPV) vaccination: global uptake and the impact of attitudes

Human papillomavirus (HPV) is the causative agent in cervical cancer and has been implicated in a range of other malignancies. Preventative vaccines are now internationally available and provide high levels of protection from common viral strains. The introduction of a comprehensive vaccination programme (except 'program' in computers) could prevent over 60% of current cervical cancer cases, but this is dependent on such programmes achieving a high level of coverage. In this review, we summarise the current trends in female HPV vaccination coverage throughout the world, and place it in the context of available research on attitudes towards vaccination amongst the public and health professionals. Where countries have the resources for mass vaccination programmes, uptake has varied. School-based opt-out programmes consistently achieve highest coverage, whilst countries and regions without systematic vaccination schemes have low coverage. In all countries, the success of vaccination programmes is dependent on the support of the public and healthcare professionals. Whilst public acceptance is dependent on multiple factors, it has repeatedly been shown that recommendation by a health professional, particularly clinicians, is key to vaccine uptake. Worryingly, it appears that a proportion of clinicians still have significant reservations about promoting vaccination, particularly for younger age groups. A commitment now, to fully educating both the public and clinicians, has the potential to make a dramatic future impact.

Inference of type-specific HPV transmissibility, progression and clearance rates: a mathematical modelling approach

Quantifying rates governing the clearance of Human Papillomavirus (HPV) and its progression to clinical disease, together with viral transmissibility and the duration of naturally-acquired immunity, is essential in estimating the impact of vaccination programmes and screening or testing regimes. However, the complex natural history of HPV makes this difficult. We infer the viral transmissibility, rate of waning natural immunity and rates of progression and clearance of infection of 13 high-risk and 2 non-oncogenic HPV types, making use of a number of rich datasets from Sweden. Estimates of viral transmissibility, clearance of initial infection and waning immunity were derived in a Bayesian framework by fitting a susceptible-infectious-recovered-susceptible (SIRS) transmission model to age- and type-specific HPV prevalence data from both a cross-sectional study and a randomised controlled trial (RCT) of primary HPV screening. The models fitted well, but over-estimated the prevalence of four high-risk types with respect to the data. Three of these types (HPV-33, -35 and -58) are among the most closely related phylogenetically to the most prevalent HPV-16. The fourth (HPV-45) is the most closely related to HPV-18; the second most prevalent type. We suggest that this may be an indicator of cross-immunity. Rates of progression and clearance of clinical lesions were additionally estimated from longitudinal data gathered as part of the same RCT. Our estimates of progression and clearance rates are consistent with the findings of survival analysis studies and we extend the literature by estimating progression and clearance rates for non-16 and non-18 high-risk types. We anticipate that such type-specific estimates will be useful in the parameterisation of further models and in developing our understanding of HPV natural history.

The cost effectiveness of human papillomavirus vaccines: a systematic review

INTRODUCTION

Human papillomavirus (HPV) is one of the world's most common sexually transmitted infections, and has been associated with a number of cervical and non-cervical diseases, including cancer. HPV vaccines have been licensed for use in females for some time, but the quadrivalent vaccine has only recently become licensed for use in males. Many countries have adopted a vaccination programme for adolescent females based on results of cost-effectiveness analyses. However, given the new indications for use of the vaccine in males, decision makers require information on the cost effectiveness of vaccinating males in order to make policy decisions on whether or not to fund such programmes.

OBJECTIVE

Our objective was to conduct a qualitative systematic review to update a previously conducted review of HPV vaccine studies.

METHODS

Articles were obtained from an extensive literature search to determine the cost effectiveness of implementing an HPV vaccination programme with routine cervical cancer screening. A total of 29 studies were included in this review. Seventeen of the included articles looked only at cervical disease outcomes, and 12 studies also included non-cervical disease outcomes. Four studies explored the economic impact of vaccinating both boys and girls. One study focused on a population of men who have sex with men (MSM).

RESULTS

While different model structures, input parameters and baseline assumptions were used, the consistent message in studies that focused on female-only vaccination programmes was that routine vaccination of females is cost effective compared with cervical cancer screening alone.

DISCUSSION

Based on the currently available literature, it appears that the addition of boys to a vaccination programme generally exceeds traditional cost-effectiveness thresholds. The MSM population represents a potential additional target for routine HPV vaccination; however, more cost-effectiveness studies are required before making such a policy change.

Geographic poverty and racial/ethnic disparities in cervical cancer precursor rates in Connecticut, 2008-2009

OBJECTIVES

We examined associations of geographic measures of poverty, race, ethnicity, and city status with rates of cervical intraepithelial neoplasia grade 2 or higher and adenocarcinoma in situ (CIN2+/AIS), known precursors to cervical cancer.

METHODS

We identified 3937 cases of CIN2+/AIS among women aged 20 to 39 years in statewide surveillance data from Connecticut for 2008 to 2009. We geocoded cases to census tracts and used census data to calculate overall and age-specific rates. Poisson regression determined whether rates differed by geographic measures.

RESULTS

The average annual rate of CIN2+/AIS was 417.6 per 100,000 women. Overall, higher rates of CIN2+/AIS were associated with higher levels of poverty and higher proportions of Black residents. Poverty was the strongest and most consistently associated measure. However, among women aged 20 to 24 years, we observed inverse associations between poverty and CIN2+/AIS rates.

CONCLUSIONS

Disparities in cervical cancer precursors exist for poverty and race, but these effects are age dependent. This information is necessary to monitor human papillomavirus vaccine impact and target vaccination strategies.

Efficacy of vaccination against HPV infections to prevent cervical cancer in France: present assessment and pathways to improve vaccination policies

BACKGROUND

Seventy percent of sexually active individuals will be infected with Human Papillomavirus (HPV) during their lifetime. These infections are incriminated for almost all cervical cancers. In France, 3,068 new cases of cervical cancer and 1,067 deaths from cervical cancer occurred in 2005. Two vaccines against HPV infections are currently available and vaccination policies aim to decrease the incidence of HPV infections and of cervical cancers. In France, vaccine coverage has been reported to be low.

METHODS

We developed a dynamic model for the heterosexual transmission of Human Papillomavirus types 16 and 18, which are covered by available vaccines. A deterministic model was used with stratification on gender, age and sexual behavior. Immunity obtained from vaccination was taken into account. The model was calibrated using French data of cervical cancer incidence.

RESULTS

In view of current vaccine coverage and screening, we expected a 32% and 83% reduction in the incidence of cervical cancers due to HPV 16/18, after 20 years and 50 years of vaccine introduction respectively. Vaccine coverage and screening rates were assumed to be constant. However, increasing vaccine coverage in women or vaccinating girls before 14 showed a better impact on cervical cancer incidence. On the other hand, performing vaccination in men improves the effect on cervical cancer incidence only moderately, compared to strategies in females only.

CONCLUSION

While current vaccination policies may significantly decrease cervical cancer incidence, other supplementary strategies in females could be considered in order to improve vaccination efficacy.

Incorporating calibrated model parameters into sensitivity analyses: deterministic and probabilistic approaches

OBJECTIVE

The aim of this study was to examine how calibration uncertainty affects the overall uncertainty of a mathematical model and to evaluate potential drivers of calibration uncertainty.

METHODS

A lifetime Markov model of the natural history of human papillomavirus (HPV) infection and cervical disease was developed to assess the cost effectiveness of a hypothetical HPV vaccine. Published data on cervical cancer incidence and mortality and prevalence of pre-cursor lesions were used as endpoints to calibrate the age- and HPV-type-specific transition probabilities between health states using the Nelder-Mead simplex method of calibration. A conventional probabilistic sensitivity analysis (PSA) was performed to assess uncertainty in vaccine efficacy, cost and utility estimates. To quantify the uncertainty around calibrated transition probabilities, a second PSA (calibration PSA) was performed using 25 distinct combinations of objective functions and starting simplexes.

RESULTS

The initial calibration produced an incremental cost-effectiveness ratio (ICER) of $US 4300 per QALY for vaccination compared with no vaccination, and the conventional PSA gave a 95% credible interval of dominant to $US 9800 around this estimate (2005 values). The 95% credible interval for the ICERs in the calibration PSA ranged from $US 1000 to $US 37,700.

CONCLUSIONS

Compared with a conventional PSA, the calibration PSA results reveal a greater level of uncertainty in cost-effectiveness results. Sensitivity analyses around model calibration should be performed to account for uncertainty arising from the calibration process.

Spotlight on AS04-adjuvanted human papillomavirus (HPV) types 16 and 18 vaccine (Cervarix®)

The AS04-adjuvanted human papillomavirus (HPV) 16/18 vaccine (Cervarix®) is a noninfectious recombinant vaccine produced using purified virus-like particles (VLPs) that induce a strong immunogenic response eliciting high levels of anti-L1 VLP antibodies that persist at levels markedly greater than those observed with natural infection. The vaccine adjuvant (AS04) is composed of monophosphoryl-lipid A, which enhances cellular and humoral immune response, adsorbed to aluminum hydroxide. The vaccine is indicated for the prevention of premalignant cervical lesions and cervical cancer causally related to certain oncogenic HPV types in females aged ≥10 years. The AS04-adjuvanted HPV 16/18 vaccine, administered via an intramuscular injection in a three-dose schedule over 6 months, elicits a high immunogenic response and is highly protective against cervical intraepithelial neoplasia and infection causally related to high-risk oncogenic HPV types. In well designed clinical trials in young women aged 15-25 years who were HPV 16/18 seronegative and DNA negative to 14 HPV high-risk types, high levels of immunogenicity and protection were sustained for follow-up periods of up to 8.4 years. High and persistent immunogenicity against infection with HPV 16/18 has also been demonstrated in older and younger females (aged 10-55 years) who were seronegative for vaccine HPV types. The AS04-adjuvanted HPV 16/18 vaccine elicited a greater immunogenic response than the quadrivalent HPV vaccine in women aged 18-45 years who were seronegative and DNA negative for HPV 16/18. The AS04-adjuvanted HPV 16/18 vaccine confers cross protection against certain non-vaccine, high-risk HPV types. A rapid and strong anamnestic humoral immune response was elicited following a fourth dose of the vaccine. The AS04-adjuvanted HPV 16/18 vaccine is generally well tolerated, and pharmacoeconomic analyses have demonstrated the potential for public health benefits and cost effectiveness when vaccination programs are run in conjunction with screening programs. Thus, the AS04-adjuvanted HPV 16/18 vaccine prevents cervical disease associated with certain oncogenic HPV types, thereby reducing the burden of premalignant cervical lesions and, very likely, cervical cancer.

The impact of cytology screening and HPV vaccination on the burden of cervical cancer

AIM

To evaluate the impact of different strategies of human papillomavirus (HPV) vaccination on the burden of cervical cancer in Singapore.

METHODS

The incidence of cervical cancer was calculated using a Markov model with inputs based on Singapore data for the prevalence of HPV infection, socioeconomic characteristics and screening prevalence. The evaluation was performed for 10 scenarios: no screening, current opportunistic cytology screening, ideal optimal screening, universal adolescent HPV vaccination at 12-years old alone and with catch-up cohorts and combinations of screening and vaccination.

RESULTS

(1) The model prediction showed that cervical cancer cases were reduced by 6.5% using opportunistic screening, by 34.3% using optimized screening and by 63.9% with a universal HPV vaccination at 12 years of age. (2) Adding optimized screening, but not opportunistic screening, to a universal adolescent HPV vaccination program caused a moderate further reduction in cervical cancer cases. (3) No difference was discernable in the impact of vaccination introduction between the age groups <20, 20-24 and 25-29 years old. (4) The time required to halve the incidence of cervical cancer was 42 years for universal vaccination at the age of 12 but could be shortened by including catch-up cohorts of women up to 40-years old.

CONCLUSION

A universal HPV vaccination program introduced between the ages of 12-29 is superior to cytology screening in reducing the burden of cervical cancer. However, in the next four decades of post-vaccination era, optimizing the screening program remains the most important measure for cervical cancer prevention.

AS04-adjuvanted human papillomavirus (HPV) types 16 and 18 vaccine (Cervarix®): a review of its use in the prevention of premalignant cervical lesions and cervical cancer causally related to certain oncogenic HPV types

The AS04-adjuvanted human papillomavirus (HPV) 16/18 vaccine (Cervarix®) is a noninfectious recombinant vaccine produced using purified virus-like particles (VLPs) that induce a strong immunogenic response eliciting high levels of anti-L1 VLP antibodies that persist at levels markedly greater than those observed with natural infection. The vaccine adjuvant (AS04) is composed of monophosphoryl-lipid A, which enhances cellular and humoral immune response, adsorbed to aluminium hydroxide. The vaccine is indicated for the prevention of premalignant cervical lesions and cervical cancer causally related to certain oncogenic HPV types in females aged ≥10 years. The AS04-adjuvanted HPV 16/18 vaccine administered in a three-dose schedule over 6 months elicits a high immunogenic response and is highly protective against cervical intraepithelial neoplasia and infection causally related to high-risk oncogenic HPV types. In well designed clinical trials in young women aged 15-25 years who were HPV 16/18 seronegative and DNA negative to 14 HPV high-risk types, high levels of immunogenicity and protection were sustained for follow-up periods of up to 8.4 years. High and persistent immunogenicity against infection with HPV 16/18 has also been demonstrated in older and younger females (aged 10-55 years) who were seronegative for vaccine HPV types. The AS04-adjuvanted HPV 16/18 vaccine elicited a greater immunogenic response than the quadrivalent HPV vaccine in women aged 18-45 years who were seronegative and DNA negative for HPV 16/18. The AS04-adjuvanted HPV 16/18 vaccine confers cross protection against certain non-vaccine, high-risk HPV types. A rapid and strong anamnestic humoral immune response was elicited following a fourth dose of the vaccine. The AS04-adjuvanted HPV 16/18 vaccine is generally well tolerated, and pharmacoeconomic analyses have demonstrated the potential for public health benefits and cost effectiveness when vaccination programmes are run in conjunction with screening programmes. Thus, the AS04-adjuvanted HPV 16/18 vaccine prevents cervical disease associated with certain oncogenic HPV types, thereby reducing the burden of premalignant cervical lesions and, very likely, cervical cancer.

Calibrating longitudinal models to cross-sectional data: the effect of temporal changes in health practices

OBJECTIVES

To assess the impact of simulating temporal changes in health-care practice patterns when calibrating longitudinal models to cross-sectional data.

METHODS

A Markov model of cervical cancer was calibrated to recent age-specific US data on the prevalence of cervical abnormalities, cervical cancer incidence, and related mortality. The impact of failing to account for temporal changes in screening practices was assessed by comparing results from 1) a conventional calibration that incorrectly assumed that all women had been exposed to current screening practices in the past and 2) an historically accurate calibration that reflected the fact that US women 65 years of age and older had not received currently available screening practices at younger ages.

RESULTS

The parameter set derived from conventional calibration produced a cervical cancer incidence rate of 13.4 per 100,000 among women aged 65 years and older, which is equal to the target end point. However, when this parameter set was used in the model to simulate the effects of historically correct screening, cervical incidence and related mortality in the 65 years and older age group were overestimated by 18% and 47%, respectively. Finally, when the parameter set was correctly calibrated by assuming historical changes in screening in the calibration process, excellent calibration to both incidence and mortality was obtained.

CONCLUSIONS

Calibrating longitudinal models to cross-sectional data without accounting for temporal changes in clinical practice may result in a parameter set that is not as optimized as it appears and may lead to bias in evaluating the effectiveness of interventions.

Increasing rates of cervical cancer in young women in England: an analysis of national data 1982-2006

Background:

In England, cervical cancer is the second most common cancer in women aged under 35 years. Overall incidence of cervical cancer has decreased since the introduction of the national screening programme in 1988 but recent trends of incidence in young women have not been studied in detail.

Methods:

Information on 71 511 incident cases of cervical cancer in England, 1982–2006, in 20–79-year-olds was extracted from a national cancer registration database. Changes in incidence were analysed by age group, time period and birth cohort. Poisson regression was used to estimate annual percentage change (APC).

Results:

Overall incidence, during 1982–2006, fell significantly from 213 to 112 per million person years. However, in 20–29-year-olds, after an initial fall, incidence increased significantly during 1992–2006, (APC 2.16). In 30–39-year-olds incidence stabilised during the latter part of the study period. The pattern was most marked in the North East, Yorkshire and the Humber and East Midlands regions. Birth cohorts that were initially called for screening between 60–64 and 35–39 years of age show an incidence peak soon after the age of presumed first screen, whereas younger birth cohorts show a peak at about 35 years of age. Incidence in the 1977–1981 birth cohort has increased relative to that among women born between 1962 and 1976.

Conclusion:

These results have implications for cervical screening, human papilloma virus vaccination and other public health interventions targeting young people.

Cost-effectiveness of different human papillomavirus vaccines in Singapore

Background

Human papillomavirus (HPV) vaccines are widely available and there have been studies exploring their potential clinical impact and cost-effectiveness. However, few studies have compared the cost-effectiveness among the 2 main vaccines available - a bivalent vaccine against HPV 16/18, and a quadrivalent vaccine against 6/11/16/18. We explore the cost-effectiveness of these two HPV vaccines in tropical Singapore.

Methods

We developed a Markov state-transition model to represent the natural history of cervical cancer to predict HPV infection, cancer incidence, mortality, and costs. Cytologic screening and treatment of different outcomes of HPV infection were incorporated. Vaccination was provided to a cohort of 12-year old females in Singapore, followed up until death. Based on available vaccines on the market, the bivalent vaccine had increased effectiveness against a wider range of HPV types, while the quadrivalent vaccine had effectiveness against genital warts. Incremental cost-effectiveness ratios (ICER) compared vaccination to no-vaccination, and between the two vaccines. Sensitivity analyses explored differences in vaccine effectiveness and uptake, and other key input parameters.

Results

For the no vaccination scenario, 229 cervical cancer cases occurred over the cohort's lifetime. The total discounted cost per individual due to HPV infection was SGD$275 with 28.54 discounted life-years. With 100% vaccine coverage, the quadrivalent vaccine reduced cancers by 176, and had an ICER of SGD$12,866 per life-year saved. For the bivalent vaccine, 197 cancers were prevented with an ICER of $12,827 per life-year saved. Comparing the bivalent to the quadrivalent vaccine, the ICER was $12,488 per life-year saved. However, the cost per QALY saved for the quadrivalent vaccine compared to no vaccine was $9,071, while it was $10,392 for the bivalent vaccine, with the quadrivalent vaccine dominating the bivalent vaccine due to the additional QALY effect from reduction in genital warts. The overall outcomes were most sensitive to vaccine cost and coverage.

Conclusion

HPV vaccination is a cost-effective strategy, and should be considered a possible strategy to reduce the impact of HPV infection.

The role of optimal control in assessing the most cost-effective implementation of a vaccination programme: HPV as a case study

Vaccination against the human papillomavirus (HPV) is a recent development in the UK. This paper uses an optimal control model to explore how best to target vaccination. We find that the vaccination of sexually active individuals has a greater impact on disease control than the vaccination of sexually non-active individuals. Extending the model to include male vaccination, we find that including males in a vaccination strategy is cost-effective. We compare the optimal control solution to that from a constant control model and show that the optimal control model is more efficient at forcing the system to a disease-controlled steady state.

A comparison of HPV DNA testing and liquid based cytology over three rounds of primary cervical screening: extended follow up in the ARTISTIC trial

BACKGROUND

The additional sensitivity of HPV testing compared with cytology could permit extended cervical screening intervals. We wished to determine, through a further (third) round of screening in the ARTISTIC trial, the protection provided by a negative baseline HPV screen compared with that of cytology over a 6 year period.

METHODS

Cumulative rates of CIN2 or worse (CIN2+) and CIN3 or worse (CIN3+) were correlated with baseline HPV status and cytology. HPV was detected using the Hybrid Capture 2 (Qiagen) assay for high risk types and genotyped using the Linear Array (Roche) and Papillocheck (Greiner) assays. LBC was performed using ThinPrep (Hologic).

FINDINGS

Round 3 included 8,873 women of whom 6,337 had been screened in both rounds 1 and 2 and 2,536 had not been screened since round 1. The median duration of follow-up was 72.7 months. The cumulative rate of CIN2+ over three rounds was 3.88% (95%CI 3.59%, 4.17%) overall; 2.39% in round 1, 0.78% in round 2 and 0.74% in round 3. Cumulative rates by baseline status were 20.53% (95%CI 19.04%, 22.08%) for abnormal cytology, 20.12% (95%CI 18.68%, 21.61%) for HPV detection, 1.41% (95%CI 1.19%, 1.65%) for negative cytology and 0.87% (95%CI 0.70%, 1.06%) for a negative HPV test. In HPV negative women aged over 50 the cumulative rate was 0.16% (95%CI 0.07%, 0.34%). Women who were HPV positive/cytology negative at entry had a cumulative CIN2+ rate of 7.73% (95%CI 6.29%, 9.36%) over 6 years, twice the overall rate.

INTERPRETATION

A negative HPV test was significantly more protective than normal cytology over three rounds. The findings of this extension of ARTISTIC suggest that the screening interval could be extended to 6 years if HPV testing replaced cytology as the primary screening test.

The importance of social norms for uptake of catch-up human papillomavirus vaccination in young women

Background Human papillomavirus (HPV) is the cause of almost all cases of cervical cancer. The current UK government immunisation program includes free routine HPV vaccination of girls aged 12–13, with a catch-up vaccination program for 13–18-year-old girls. The aim of this study was to identify correlates of intended and actual uptake of catch-up HPV vaccination. Methods: An online questionnaire was completed by 591 young women aged 16–20. Results: Of the 350 women who had been offered catch-up HPV vaccination, 90.6% had accepted. In multivariate analyses, vaccine uptake was significantly correlated with subjective norms more supportive of HPV vaccination, and greater uptake of other childhood vaccinations (χ2(3) = 39.34, P < 0.01; 91.1% correctly classified; Nagelkerke pseudo-r2 = 0.23). Among the 241 women aged 16–20 who had not been offered HPV vaccination, the average intention was 3.70 on a five-point scale. Multivariate analyses revealed four significant independent predictors of stronger intentions to accept vaccination: subjective norms more supportive of HPV vaccination, greater worry about sexually transmissible infections, greater support for young people’s sexual health services and greater support for childhood vaccination (F(4,236) = 18.67, P < 0.01; adjusted r2 = 0.23). Young women rated television advertisements, educational programs and television soaps as the most effective ways to encourage uptake of HPV vaccination. Conclusions: Uptake of HPV vaccination may be increased if interventions use appropriate media to promote social norms supportive of HPV vaccination.

A generally applicable cost-effectiveness model for the evaluation of vaccines against cervical cancer

Objective

This study aimed at evaluating the cost-effectiveness of human papillomavirus virus (HPV) vaccination in France, using a generally applicable succinct cohort model.

Methods

A lifetime Markov cohort model, adapted to the French setting, simulate the natural history of oncogenic HPV infection towards cervical cancer (CC). Additional modules account for the effects of screening and vaccination. The girls’ cohort is vaccinated at age 12 and follows current screening. Costs and outcomes (discounted at 3 and 1.5%, respectively) were compared with a cohort receiving screening alone.

Results

The model results agreed well with real-life data. Vaccination in addition to screening would substantially reduce the incidence of and mortality from CC, compared with screening alone, at an estimated cost-effectiveness of €9,706 per quality-adjusted-life-year. Sensitivity analysis showed that the discount rate and the parameters related to the disease history have the largest impact on the results.

Conclusion

This succinct cohort model indicated that HPV vaccination would be a cost-effective policy option in France. It uses readily available data and should be generally applicable to the evaluation of HPV vaccination in a variety of countries and settings.

Using simulation-optimization to construct screening strategies for cervical cancer

Cervical cancer is the second most common cancer in women worldwide. Cervical screening is critical for preventing this type of cancer. Traditionally, screening strategies are evaluated from an economic point of view through cost-effectiveness analysis. However, cost-effectiveness analysis is typically performed on a limited number of de facto or predetermined screening policies. We develop a simulation-optimization model to determine the ages at which screening should be performed, resulting in dynamic, age-based screening policies. We consider three performance measures: cervical cancer incidence, the number of cervical cancer deaths, and the number of life years lost due to cervical cancer death. Using each performance measure, we compare our optimal, dynamic screening strategies to standard policies considered in the health screening literature that are static and predetermined. We also evaluate the anticipated impact of vaccinations for preventing cervical cancer. The strategies that are developed are compared to those used in practice or considered in the literature. The Centers for Disease Control and Prevention recommends one screening every 3 years, resulting in 14 scheduled lifetime screenings. Our dynamic screening strategies provide approximately the same health benefits as this but with four to six fewer scheduled screenings, depending on the performance measure considered. Our dynamic strategies also provide approximately the same health benefits as screening every 2 years, but with six to nine fewer scheduled screenings. The results suggest that dynamic, age-based cervical cancer screening policies offer substantial economic savings in order to offer the same health benefits as equally spaced screening strategies.

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.

Human papillomavirus vaccination and social inequality: results from a prospective cohort study

We investigated the effect of social inequalities on the uptake of human papillomavirus (HPV) vaccination, combining data from a feasibility study conducted in 2007–2008 in 2817 secondary schoolgirls in two UK primary-care trusts, with census and child health records. Uptake was significantly lower in more deprived areas (P<0·001) and in ethnic minority girls (P=0·013). The relatively small proportion of parents who actively refused vaccination by returning a negative consent form were more likely to come from more advantaged areas (P<0·001). Non-responding parents were from more deprived (P<0·001) and ethnic minority (P=0·001) backgrounds. Girls who did not receive HPV vaccination were less likely to have received all their childhood immunizations particularly measles, mumps and rubella (MMR). Different approaches may be needed to maximize HPV vaccine uptake in engaged and non-responding parents, including ethnic-specific approaches for non-responders.

Methods of model calibration: observations from a mathematical model of cervical cancer

BACKGROUND

Mathematical models are commonly used to predict future benefits of new therapies or interventions in the healthcare setting. The reliability of model results is greatly dependent on accuracy of model inputs but on occasion, data sources may not provide all the required inputs. Therefore, calibration of model inputs to epidemiological endpoints informed by existing data can be a useful tool to ensure credibility of the results.

OBJECTIVE

To compare different computational methods of calibrating a Markov model to US data.

METHODS

We developed a Markov model that simulates the natural history of human papillomavirus (HPV) infection and subsequent cervical disease in the US. Because the model consists of numerous transition probabilities that cannot be directly estimated from data, calibration to multiple disease endpoints was required to ensure its predictive validity. Goodness of fit was measured as the mean percentage deviation of model-predicted endpoints from target estimates. During the calibration process we used the manual, random and Nelder-Mead calibration methods.

RESULTS

The Nelder-Mead and manual calibration methods achieved the best fit, with mean deviations of 7% and 10%, respectively. Nelder-Mead accomplished this result with substantially less analyst time than the manual method, but required more intensive computing capability. The random search method achieved a mean deviation of 39%, which we considered unacceptable despite the ease of implementation of that method.

CONCLUSIONS

The Nelder-Mead and manual techniques may be preferable calibration methods based on both performance and efficiency, provided that sufficient resources are available.

Cost effectiveness of prophylactic HPV 16/18 vaccination in Finland: results from a modelling exercise

OBJECTIVES

the study aims to estimate the clinical-impact and cost-effectiveness value of adding human papillomavirus 16/18 vaccination against cervical cancer among women currently undergoing organised screening in Finland.

METHODS

A Markov cohort model evaluating high-risk HPV infections and cervical cancer (CC) cases combined with screening has been customised to the Finnish setting. The model outcome for a cohort of 30,000 girls aged 10 years was calibrated to age-specific annual number of Pap smears, CC incidence and mortality.

RESULTS

The observed age-specific incidence and mortality rates of CC closely match the data replicated by the model. The model predicts that with a 90% vaccine coverage rate, CC cases and mortality would be reduced by 70%. In the base-case analysis with a discount rate of 3% the incremental cost per quality-adjusted life-years (QALY) gained, from a healthcare perspective, was €17,294. Without discounting this value is €2,591/QALY gained.

CONCLUSIONS

The analysis suggests that implementing prophylactic CC vaccination within the current screening system would substantially reduce CC cases and deaths, as well as the overall disease burden expressed in pre-cancer lesions averted. Vaccination could be a cost-effective intervention in Finland despite the fact that the number of CC cases and deaths are currently relatively low. Conservative estimates of the cost effectiveness of the vaccination were provided since it was not possible to assess herd protection induced by vaccination using this Markov model.

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.

Ethnic differences in human papillomavirus awareness and vaccine acceptability

Background:

Studies of human papillomavirus (HPV) awareness and HPV vaccine acceptability have included few non-white participants, making it difficult to explore ethnic differences. This study assessed HPV awareness and HPV vaccine acceptability in a sample of women representing the major UK ethnic minority groups.

Methods:

A cross-sectional study design was used to assess awareness of HPV and acceptability of HPV vaccination. Participants were recruited using quota sampling to ensure adequate representation of ethnic minority women: Indian, Pakistani, Bangladeshi, Caribbean, African and Chinese women (n = 750). A comparison sample of white British women (n = 200) was also recruited.

Results:

Awareness of HPV was lower among ethnic minority women than among white women (6–18% vs 39% in white women), and this was not explained by generational status or language spoken at home. In a subsample who were mothers (n = 601), ethnicity and religion were strongly associated with acceptability of HPV vaccination. Acceptability was highest among white mothers (63%) and lowest among South Asians (11–25%). Those from non-Christian religions were also less accepting of the vaccine (17–34%). The most common barriers to giving HPV vaccination were a need for more information, sex-related concerns and concern about side-effects. South Asian women were the most likely to cite sex-related concerns, and were also least likely to believe the vaccine would offer their daughters protection.

Conclusion:

These findings suggest some cultural barriers that could be addressed in tailored information aimed at ethnic minority groups. They also highlight the importance of recording ethnicity as part of HPV vaccine uptake data.