Projected Clinical Benefits and Cost-effectiveness of a Human Papillomavirus 16/18 Vaccine

Examining future adolescent human papillomavirus vaccine uptake, with and without a school mandate

PURPOSE

To develop a model of adolescent (HPV) human papillomavirus vaccine utilization that explored future HPV vaccination rates, with and without a school mandate, for the vaccine at middle school entry.

METHODS

A dynamic, population-based, compartmental model was developed that estimated over a 50-year time horizon HPV vaccine uptake among female adolescents living in the United States. The model incorporated data on parental attitudes about this vaccine and adolescent health care utilization levels.

RESULTS

Without a mandate, our model predicted that 70% coverage, a lower threshold value used in many previous modeling studies of HPV vaccination, would not be achieved until a mean of 23 years after vaccine availability. Maximal coverage of 79% was achieved after 50 years. With a school mandate in place, utilization increased substantially, with 70% vaccination coverage achieved by year 8 and maximal vaccination coverage, 90%, achieved by year 43.

CONCLUSIONS

Our results suggest that vaccine utilization is likely to be low for several years, though strong school mandates might improve HPV vaccine uptake. These results affect the interpretation of previous modeling studies that estimated the potential clinical effects of HPV vaccination under assumptions of very high vaccine utilization rates.

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 vaccine update

With the approval of Gardasil (Merck and Co., Inc., Whitehouse Station, NJ) in June of 2006 and the pending approval of Cervarix (GlaxoSmithKline, London, UK), two prophylactic human papillomavirus (HPV) vaccines will be available for clinical use. Randomized controlled trials have shown that both vaccines are safe and highly effective in preventing persistent infection and lesions caused by HPV 16 and 18--the types responsible for 70% of cervical cancers worldwide. Determining an effective vaccination strategy is now the most pressing issue facing clinicians, parents, public health officials, and policy makers. We discuss the appropriate age of vaccination, vaccine acceptance, implementation strategies in low resource settings, and the future of screening.

Cost-effectiveness analysis of a quadrivalent human papilloma virus vaccine in Mexico

BACKGROUND AND AIMS

Cervical cancer is one of the main causes of death in women in low- and middle-income countries. Despite technological and scientific advances that allow an early detection of precancerous lesions and curative treatment of cervical cancer, Mexico and other Latin American countries have only been able to obtain a small decrease in the mortality rates for this kind of cancer. How to implement and sustain effective public health strategies for cervical cancer prevention, such as increasing cytology-based screening program coverage and implementing HPV-DNA testing and vaccination, are important questions. The aim of this study is to perform a cost-effectiveness analysis of the introduction of a quadrivalent (HPV 6/11/16/18) HPV vaccine into the public health system and evaluate the epidemiological and economic benefits on prevention of cervical cancer in Mexico.

METHODS

A Markov model is used to simulate the natural history of HPV infection in a cohort of Mexican women to evaluate the cost-effectiveness of the cervical cancer screening strategy used in Mexico as well as the benefits of other potential strategies such as 1) vaccination only, 2) conventional cytology-based screening program only and 3) vaccination followed by screening. For the strategies that involve screening we have chosen screening intervals of 3 and 5 years. The model produces results that are reasonably close to the epidemiological data related to HPV and cervical cancer in Mexico.

RESULTS

The quadrivalent HPV vaccine could reduce the probability of persistent HPV-16/18 infection by at least 60%, which would result in a near-proportional reduction in HPV-16/18-associated invasive cervical cancer and CIN 3.

CONCLUSIONS

The strategy of using only vaccination ($45 USD for three doses) as a preventive measure was a very cost-effective strategy in Mexico ($68USD/LYS). The strategy of vaccination with traditional screening of Pap test every 3 years produced higher cost by a lower performance of cervical cytology in Mexico, at a cost of $15,935 USD per life-year. The cost-effectiveness of the vaccination strategy was highly sensitive to age of vaccination, duration of vaccine efficacy, and cost of vaccination. The Mexican model predicts that a quadrivalent HPV vaccine will reduce the incidence of high- and low-risk-associated cervical cancer. A program of vaccination as a preventive strategy is likely cost effective. The results of this study could be of great value in decision-making for the implementation of an HPV vaccine as a public health policy in Mexico provided that the cost of each dose will be, at most, $15 dollars (USD) dollars, combined with HPV testing, the new strategy of national secondary prevention program.

Comparison of HPV and cytology triage algorithms for women with borderline or mild dyskaryosis in population-based cervical screening (VUSA-screen study)

We studied the effectiveness of high-risk human papillomavirus (hrHPV) triage for immediate colposcopy in women with borderline or mild dyskaryosis (BMD). In the Utrecht province of the Netherlands, women aged 30-60 years who participated in the regular cervical screening programme were offered hrHPV testing and cytology (intervention group) or cytology only (control group). In the intervention group (n = 337), women with BMD were immediately referred for colposcopy only if the sample was hrHPV positive. Women with a hrHPV negative test were advised to repeat cytology at 6 and 18 months and were referred for colposcopy if and when the repeat test result was positive (BMD or worse). In the control group (n = 329), referral of women with BMD was delayed until cytology was repeatedly positive at 6 or 18 months. The CIN3 detection rates were 10.7% (36/337) in the intervention group and 6.4% (21/329) in the control group (p = 0.047). Moreover, hrHPV triaging resulted in shorter time to diagnosis (154 vs. 381 days). Although the number of colposcopy referrals was 51.5% higher in the intervention group than in the control group, the medical costs per detected CIN3 were slightly lower ([euro] 4781 vs. [euro] 6235). If, in addition, hrHPV negative women had been referred back to routine screening at baseline, the CIN3 rate would have been 10.1% (34/337) and colposcopy rate would only have been 30.4% higher than in the control group. This study shows that hrHPV triaging of women with BMD is at least as effective for detecting CIN3 as repeat cytology, also when hrHPV negative women are referred back to routine screening.

Cost-effectiveness of 21 alternative cervical cancer screening strategies

OBJECTIVES

The aim of this study is to assess the cost-effectiveness of 21 alternative cervical cancer screening (CCS) strategies.

METHODS

A cohort simulation model was developed to determine from a health systems perspective the cost-effectiveness of the 21 alternative CCS strategies that incorporated combinations of Papanicolaou's smear test (PAP), liquid-based cytology (LBC) or human papillomavirus deoxyribonucleic acid (HPV-DNA) testing. The model was calibrated to categorize total costs into four budgetary authorities: testing, physician, inpatient, and outpatient services. Within each category, alternative screening strategies were contrasted in terms of their cost impacts and the percent change calculated within each category. Epidemiologic data and costs were derived from administrative health databases. Estimates of test characteristics and quality-adjusted life years (QALYs) were derived from available literature.

RESULTS

Three-year screening with PAP and HPV-DNA triage testing for women older than 30 years of age (3-year PAP+HPV+PAP-age) is less costly and more effective saving $16,078 per additional QALY gained. Although there was an associated net cost decrease of 4.2% driven by a reduction in testing and physician costs of 22.1% and 18.6%, respectively, there is a cost increase of 0.8% and 27.7% in inpatient and outpatient services, respectively.

CONCLUSION

There is economic evidence to support adopting 3-year PAP+HPV+PAP-age. Budgetary resources can potentially be shifted from testing and physician services to fund the additional resource requirements for inpatient and outpatient services.

The Health Technology Assessment of bivalent HPV vaccine Cervarix in Italy

INTRODUCTION

Health Technology Assessment (HTA) approach was applied to Human Papilloma Virus (HPV) vaccine in the Italian context.

METHODS

Epidemiology and costs of HPV infection and related diseases, vaccine efficacy, clinical and economic impact of the HPV vaccination and women's knowledge and attitudes towards vaccination were assessed.

RESULTS

HPV infections pooled prevalence in Italy was 19% (95%CI: 10-30%) and cervical cancer incidence was 9.8/100,000 per year. The mean costs for in situ and invasive carcinoma hospitalisation were estimated respectively in euro1745.87 and euro2616.16. HPV vaccines have demonstrated high efficacy and good safety profile. The meta-analysis on efficacy results in preventing persistent cervical infections by HPV16 and 18 for both HPV vaccines resulted in 87% (95%CI: 80-91%) and 78% (95%CI: 62-87%). Modelling the impact of vaccination with bivalent vaccine, it would reduce cancer cases by 67% and be cost-effective, with a cost per Quality Adjusted Life Years (QALYs) gained of euro22,055.

CONCLUSION

The thoroughness of the evaluation allowed us accounting for all the aspects of HPV infection/diseases. The HTA report on the HPV vaccine demonstrated to be a comprehensive tool for an informed decision making process.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A brief history of economic evaluation for human papillomavirus vaccination policy

Background: This commentary discusses key issues for health economic evaluation and modelling, applied to human papillomavirus (HPV) vaccine programs. Methods: We outline some of the specific features of HPV disease and vaccination, and associated policy questions in light of a literature search for economic evaluations on HPV vaccination. Results: We observe that some policy questions could not be reliably addressed by many of the 43 published economic evaluations we found. Despite this, policy making on universal HPV vaccination followed shortly after vaccine licensure in many developed countries, so the role economic evaluation played in informing these decisions (pre-dating 2008) seems to have been fairly limited. For more recent decisions, however, economic evaluation is likely to have been used more widely and more intensively. Conclusions: We expect future cost-effectiveness analyses to be more instrumental in policy making regarding vaccines covering more HPV types, therapeutic HPV vaccines, and novel diagnostic tests for biomarkers of HPV infection and disease integrated with cervical screening programs.

Human papillomavirus infections among couples in new sexual relationships

BACKGROUND

No studies have examined human papillomavirus (HPV) infections among couples early in their sexual relationships when transmission is most likely. Our objective was to describe the distribution of HPV infections among recently formed couples, using the partnership as the unit of analysis.

METHODS

Women aged 18-24 years attending a university or junior college in Montreal enrolled in a longitudinal study with their new male partners. Self-collected vaginal swabs and clinician-collected swabs from the penis and scrotum were tested for 36 HPV genotypes. Participants self-reported sexual behavior in computerized questionnaires. We analyzed patterns of genital HPV infection in 263 couples using data obtained at enrollment.

RESULTS

Couples had engaged in vaginal sex for a median of 3.9 months. HPV was detected in 64% (169/263) of couples. In 41% (109/263), both partners harbored the same HPV type-nearly 4 times more than expected if HPV status of partners were uncorrelated. There were 583 type-specific HPV infections among 169 couples for whom at least one partner was infected. Of these, 42% were of the same type for both partners (95% confidence interval = 36%-47%). This rose from 25% among those engaging in vaginal sex for less than 2 months to 68% among those at 5 to 6 months.

CONCLUSIONS

Although HPV is common, detection of the same type in persons initiating a sex relationship would be rare given type-specific prevalence rates. The high degree of concordance we found suggests a high probability of transmission.

Modelling the economic value of cross- and sustained-protection in vaccines against cervical cancer

OBJECTIVE

Two human papillomavirus (HPV) vaccines are on the market. Based on expected differences in sustained- and cross-protection between the two vaccines, their long-term economic value is modelled and compared for France, Ireland and Italy.

METHODS

A Markov cohort model reproducing the natural history of HPV infections, screening and vaccination, is adapted to country-specific data. Two hypothetical HPV vaccines (VA and VB) are compared. At baseline VA provides lifetime protection against HPV-16 and 10-year protection against HPV-18 before waning. VB is the same as VA with a 10-year protection against HPV-6 and 11. Sustained- and cross-protection is varied over wide ranges in VA to define the levels that could make VA cost-effective or dominant compared with VB.

RESULTS

Under baseline conditions VB dominates VA. VA becomes cost-effective when the difference in cross-protection alone reaches 13-15% (undiscounted), and 22-44% (discounted). A combination of sustained- and cross-protection is required for VA to dominate VB (discounted). The results are dependent upon country, the base-case value and the discount applied.

CONCLUSION

Realistic additional sustained- and cross-protection in one HPV vaccine may confer benefits that offset the economic value of protection against low-risk HPV in the other. The results are country specific.

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.

Public health issues related to HPV vaccination

The human papillomavirus (HPV) is clearly established as the cause of cervical cancer, and vaccines targeting oncogenic forms of the virus are important as a primary method of prevention. However, barriers to cervical screening and vaccination such as a lack of knowledge of HPV, access to healthcare, and poor follow-up prevent the acceptance and utilization of HPV vaccines. Strategies for prevention of disease and implementation of vaccination are in development, but the importance of primary prevention of HPV infection needs to be stressed. This review assesses the potential impact of vaccination for cervical cancer, barriers to vaccination, and the methods used to increase coverage. With the advent of prophylactic vaccines, HPV, a common infection in the United States, can be prevented in most women.

Factors influencing familial decision-making regarding human papillomavirus vaccination

OBJECTIVE

The purpose of this review is to summarize the research regarding Human Papillomavirus (HPV) vaccination uptake among families with adolescent/preadolescent daughters.

METHODS

Literature searches (utilizing PubMed and PsychInfo databases) were conducted and research examining psychological and environmental factors which relate to HPV vaccine uptake and intentions was reviewed.

RESULTS

Factors such as physician recommendations, perceptions of the beliefs of peers and significant others, history of childhood immunizations, and communication with adolescents regarding sexual topics appear to influence HPV vaccination outcomes.

CONCLUSIONS

Although primary prevention of cervical and other cancers is available for preadolescent and adolescent girls, rates of HPV vaccine uptake are low. Future interventions should target vaccine intent and physician/family communication as a means to increasing HPV vaccination.

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.

Cost-effectiveness of human papillomavirus vaccination and cervical cancer screening in women older than 30 years in the United States

BACKGROUND

Women older than 30 years are the main beneficiaries of improved cervical cancer screening with human papillomavirus (HPV) DNA testing. The role of vaccination against HPV types 16 and 18, which is recommended routinely for preadolescent girls, is unclear in this age group.

OBJECTIVE

To assess the health and economic outcomes of HPV vaccination in older U.S. women.

DESIGN

Cost-effectiveness analysis with an empirically calibrated model.

DATA SOURCES

Published literature.

TARGET POPULATION

U.S. women aged 35 to 45 years.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTION

HPV vaccination added to screening strategies that differ by test (cytology or HPV DNA testing), frequency, and start age versus screening alone.

OUTCOME MEASURES

Incremental cost-effectiveness ratios (2006 U.S. dollars per quality-adjusted life-year [QALY] gained).

RESULTS OF BASE-CASE ANALYSIS

In the context of annual or biennial screening, HPV vaccination of women aged 35 to 45 years ranged from $116 950 to $272 350 per QALY for cytology with HPV DNA testing for triage of equivocal results and from $193 690 to $381 590 per QALY for combined cytology and HPV DNA testing, depending on age and screening frequency.

RESULTS OF SENSITIVITY ANALYSIS

The probability of HPV vaccination being cost-effective for women aged 35 to 45 years was 0% with annual or biennial screening and less than 5% with triennial screening, at thresholds considered good value for money.

LIMITATION

The natural history of the disease and the efficacy of the vaccine in older women are uncertain.

CONCLUSION

Given currently available information, the effectiveness of HPV vaccination for women older than 30 years who are screened seems to be small. Compared with current screening that uses sensitive HPV DNA testing, HPV vaccination is associated with less attractive cost-effectiveness ratios in this population than those for other, well-accepted interventions in the United States.

Preventing future cancers by testing women with ovarian cancer for BRCA mutations

PURPOSE

Women with ovarian cancer have a 10% probability of carrying a BRCA mutation. If a mutation is identified, unaffected family members can undergo genetic testing and cancer risk-reducing strategies. We estimated the net health benefits and cost-effectiveness of different criteria for BRCA mutation testing in women with ovarian cancer, and the downstream benefits for their first-degree relatives (FDRs).

METHODS

We developed a Markov Monte Carlo simulation model to compare four criteria for BRCA testing in women with ovarian cancer: no testing (reference); only if personal history of breast cancer, family history of breast/ovarian cancer, or Ashkenazi Jewish ancestry; only if invasive serous cancer; any invasive nonmucinous epithelial cancer. Net health benefit was life expectancy for FDRs and primary outcome was the incremental cost-effectiveness ratio (ICER). The model estimated the number of future breast and ovarian cancer cases in FDRs.

RESULTS

BRCA testing based on personal/family history and ancestry could prevent future cases in FDRs with an ICER of $32,018 per year of life (LY) gained compared with the reference strategy. BRCA testing based on serous or any nonmucinous epithelial ovarian cancer could prevent more cancer cases, but at ICERs of $128,465 and $148,363 per LY gained, respectively.

CONCLUSION

BRCA testing of women with ovarian cancer based on personal/family history of cancer or Ashkenazi Jewish ancestry is a cost-effective strategy to prevent future breast and ovarian cancers among FDRs. More inclusive testing strategies prevent additional cancer cases but at significant cost.

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.

Multiple human papillomavirus genotype infections in cervical cancer progression in the study to understand cervical cancer early endpoints and determinants

Determining the causal attribution of human papillomavirus (HPV) genotypes to cervical disease is important to estimate the effect of HPV vaccination and to establish a type spectrum for HPV-based screening. We analyzed the prevalence of HPV infections and their attribution to cervical disease in a population of 1,670 women referred to colposcopy for abnormal cytology at the University of Oklahoma. HPV genotyping was performed from cytology specimens using the Linear Array assay that detects 37 HPV genotypes. We used different methods of type attribution to revised cervical disease categories. We found very high prevalence of multiple HPV infections with up to 14 genotypes detected in single specimens. In all disease categories except for cancers, there was a significant trend of having more infections at a younger age. We did not see type interactions in multiple genotype infections. HPV16 was the most frequent genotype at all disease categories. Based on different attribution strategies, the attribution of vaccine genotypes (6, 11, 16, 18) ranged from 50.5 to 67.3% in cancers (n = 107), from 25.6 to 74.8% in CIN3 (n = 305), from 15.2 to 52.2% in CIN2 (n = 427), and from 6.6 to 26.0% in <CIN2 (n = 708). In the HSIL cytology group (n = 651), attribution ranged from 26.1 to 64.7%. The attribution of vaccine types to HSIL was substantially higher compared to the lower cytology categories. The potential range of HPV genotype attribution is wide at the disease categories <CIN2 to CIN3. Genotyping from cervical lesions and analyzing viral oncogene expression can improve estimates of HPV genotype attribution.

The burden of non-communicable diseases in South Africa

15 years after its first democratic election, South Africa is in the midst of a profound health transition that is characterised by a quadruple burden of communicable, non-communicable, perinatal and maternal, and injury-related disorders. Non-communicable diseases are emerging in both rural and urban areas, most prominently in poor people living in urban settings, and are resulting in increasing pressure on acute and chronic health-care services. Major factors include demographic change leading to a rise in the proportion of people older than 60 years, despite the negative effect of HIV/AIDS on life expectancy. The burden of these diseases will probably increase as the roll-out of antiretroviral therapy takes effect and reduces mortality from HIV/AIDS. The scale of the challenge posed by the combined and growing burden of HIV/AIDS and non-communicable diseases demands an extraordinary response that South Africa is well able to provide. Concerted action is needed to strengthen the district-based primary health-care system, to integrate the care of chronic diseases and management of risk factors, to develop a national surveillance system, and to apply interventions of proven cost-effectiveness in the primary and secondary prevention of such diseases within populations and health services. We urge the launching of a national initiative to establish sites of service excellence in urban and rural settings throughout South Africa to trial, assess, and implement integrated care interventions for chronic infectious and non-communicable diseases.

Social welfare and adolescent vaccination programs in the United States: the economic opportunities for a systematic expansion

In this article, the authors review current literature to analyze the cost-effectiveness of seven vaccines now available for adolescents and one that is in development. An analysis is also performed regarding the cutoff price that deems a vaccine "cost-effective." Often, $50,000 is the limit below which a drug is viewed as cost-effective. Our article contends that $160,000 could be a new limit below which the cost-effectiveness of a vaccine is better reflected. Based on standard economic valuations of life years in the United States and the preponderance of evidence from the cost-effectiveness literature, there is a compelling case for expanding adolescent vaccine programs, guidelines, and educational initiatives in the United States; there exist considerable economic benefits in excess of costs from policies that may achieve this objective.

The potential cost-effectiveness of adding a human papillomavirus vaccine to the cervical cancer screening programme in South Africa

This study was designed to answer the question of whether a cervical cancer prevention programme that incorporates a human papillomavirus (HPV) vaccine is potentially more cost-effective than the current strategy of screening alone in South Africa. We developed a static Markov state transition model to describe the screening and management of cervical cancer within the South African context. The incremental cost-effectiveness ratio of adding HPV vaccination to the screening programme ranged from US $1078 to 1460 per quality-adjusted life year (QALY) gained and US$3320-4495 per life year saved, mainly depending on whether the study was viewed from a health service or a societal perspective. Using discounted costs and benefits, the threshold analysis indicated that a vaccine price reduction of 60% or more would make the vaccine plus screening strategy more cost-effective than the screening only approach. To address the issue of affordability and cost-effectiveness, the pharmaceutical companies need to make a commitment to price reductions.

Epidemiology and risk factors for human papillomavirus infection in a diverse sample of low-income young women

BACKGROUND

Two HPV vaccines prevent infection with HPV-16 and HPV-18, high-risk (cancer-associated) HPV types which together cause approximately 70% of cervical cancers; one vaccine also prevents HPV-6 and HPV-11, which together cause approximately 90% of anogenital warts. Defining type-specific HPV epidemiology in sexually experienced women will help estimate the potential clinical benefits of vaccinating this population.

OBJECTIVES

To examine HPV epidemiology in a diverse sample of sexually experienced women, and to determine factors associated with high-risk HPV and vaccine-type HPV (HPV-6, HPV-11, HPV-16 and HPV-18).

STUDY DESIGN

Cross-sectional study of 13-26-year-old women (N=409) who completed a questionnaire and provided a cervicovaginal swab. Swabs were genotyped for HPV using PCR amplification. Logistic regression models were used to determine whether participant characteristics, knowledge, and behaviors were associated with high-risk and vaccine-type HPV.

RESULTS

Most women (68.4%) were positive for >or=1 HPV type, 59.5% were positive for >or=1 high-risk type, 33.1% were positive for >or=1 vaccine-type HPV, and 3.5% were positive for both HPV-16 and HPV-18: none was positive for all four vaccine types. In adjusted logistic regression models, Black race (OR 2.03, 95% CI 1.21-3.41) and lifetime number of male sexual partners (OR 4.79, 95% CI 2.04-11.23 for >or=10 partner vs. <or=1 partner) were independently associated with high-risk HPV infection.

CONCLUSIONS

HPV prevalence was very high in this sample of sexually active young women, but <5% were positive for both HPV-16 and HPV-18, suggesting that vaccination could be beneficial for many individual women who are sexually experienced.

Screening, prevention and treatment of cervical cancer -- a global and regional generalized cost-effectiveness analysis

The paper calculates regional generalized cost-effectiveness estimates of screening, prevention, treatment and combined interventions for cervical cancer. Using standardised WHO-CHOICE methodology, a cervical cancer model was employed to provide estimates of screening, vaccination and treatment effectiveness. Intervention effectiveness was determined via a population state-transition model (PopMod) that simulates the evolution of a sub-regional population accounting for births, deaths and disease epidemiology. Economic costs of procedures and treatment were estimated, including programme overhead and training costs. In regions characterized by high income, low mortality and high existing treatment coverage, the addition of any screening programme to the current high treatment levels is very cost-effective. However, based on projections of the future price per dose (representing the economic costs of the vaccination excluding monopolistic rents and vaccine development cost) vaccination is the most cost-effective intervention. In regions characterized by low income, low mortality and existing treatment coverage around 50%, expanding treatment with or without combining it with screening appears to be cost-effective or very cost-effective. Abandoning treatment in favour of screening in a no-treatment scenario would not be cost-effective. Vaccination is usually the most cost-effective intervention. Penta or tri-annual PAP smears appear to be cost-effective, though when combined with HPV-DNA testing they are not cost-effective. In regions characterized by low income, high mortality and low treatment levels, expanding treatment with or without adding screening would be very cost-effective. A one off vaccination plus expanding treatment was usually very cost-effective. One-off PAP or VIA screening at age 40 are more cost-effective than other interventions though less effective overall. From a cost-effectiveness perspective, consideration should be given to implementing vaccination (depending on cost per dose and longevity of efficacy) and screening programmes on a worldwide basis to reduce the burden of disease from cervical cancer. Treatment should also be increased where coverage is low.

Longer term efficacy of a prophylactic monovalent human papillomavirus type 16 vaccine

We conducted an extended follow-up study (March 2006-May 2008) to assess the longer term efficacy of a prophylactic monovalent human papillomavirus (HPV) type 16 L1 virus-like particle vaccine in women (n=290) who had enrolled in a randomized controlled trial of this vaccine (October 1998-November 1999) in Seattle and remained HPV-16 DNA negative during the course of that trial. During the extended follow-up period, in the per-protocol susceptible population, none of the vaccine recipients was found to be infected with HPV-16 or developed HPV-16-related cervical lesions; among placebo recipients, 6 women were found to be infected with HPV-16 (vaccine efficacy [VE]=100%; 95% confidence interval [CI]: 29-100%) and 3 women developed HPV-16-related cervical lesions (VE=100%; 95% CI: <0-100%). Approximately 86% of vaccine recipients remained HPV-16 competitive Luminex immunoassay seropositive at an average of 8.5 years of follow-up. During the combined original trial and extended follow-up period, in the intention-to-treat population, 20 and 22 women developed any cervical lesion regardless of HPV type among the vaccine and placebo recipients, respectively (VE=15%; 95% CI: <0-56%). The results suggest that this monovalent HPV-16 vaccine remains efficacious through 8.5 years after its administration.

Epidemiologic natural history and clinical management of Human Papillomavirus (HPV) Disease: a critical and systematic review of the literature in the development of an HPV dynamic transmission model

BACKGROUND

Natural history models of human papillomavirus (HPV) infection and disease have been used in a number of policy evaluations of technologies to prevent and screen for HPV disease (e.g., cervical cancer, anogenital warts), sometimes with wide variation in values for epidemiologic and clinical inputs. The objectives of this study are to: (1) Provide an updated critical and systematic review of the evidence base to support epidemiologic and clinical modeling of key HPV disease-related parameters in the context of an HPV multi-type disease transmission model which we have applied within a U.S. population context; (2) Identify areas where additional studies are particularly needed.

METHODS

Consistent with our and other prior HPV natural history models, the literature review was confined to cervical disease and genital warts. Between October 2005 and January 2006, data were gathered from the published English language medical literature through a search of the PubMed database and references were examined from prior HPV natural history models and review papers. Study design and data quality from individual studies were compared and analyses meeting pre-defined criteria were selected.

RESULTS

Published data meeting review eligibility criteria were most plentiful for natural history parameters relating to the progression and regression of cervical intraepithelial neoplasia (CIN) without HPV typing, and data concerning the natural history of HPV disease due to specific HPV types were often lacking. Epidemiologic evidence to support age-dependency in the risk of progression and regression of HPV disease was found to be weak, and an alternative hypothesis concerning the time-dependence of transition rates is explored. No data were found on the duration of immunity following HPV infection. In the area of clinical management, data were observed to be lacking on the proportion of clinically manifest anogenital warts that are treated and the proportion of cervical cancer cases that become symptomatic by stage.

CONCLUSION

Knowledge of the natural history of HPV disease has been considerably enhanced over the past two decades, through the publication of an increasing number of relevant studies. However, considerable opportunity remains for advancing our understanding of HPV natural history and the quality of associated models, particularly with respect to examining HPV age- and type-specific outcomes, and acquired immunity following infection.

The expected impact of HPV vaccination on the accuracy of cervical cancer screening: the need for a paradigm change

We used modeling approaches to estimate the impact of human papillomavirus (HPV) vaccination on the performance of Pap cytology screening under different assumptions of lesion prevalence and expected changes in sensitivity and specificity likely to prevail post-vaccination. A major driver of the efficiency and costs of screening, the positive predictive value will be severely affected if Pap cytology continues to serve as the primary screening test in the post-vaccination era. Molecular-based screening with an HPV DNA test followed by Pap triage of HPV-positive cases has the potential for circumventing this problem. As a primary screening test, HPV testing can improve the overall quality of screening programs, thus allowing for increased testing intervals that would lower program costs with acceptable safety. Cytology should be reserved for the more labor-efficient task of triaging HPV-positive cases, a situation in which case loads would be "enriched" with smears containing relevant abnormalities. HPV followed by Pap strategy can also serve a secondary role in post-vaccination surveillance.

Incorporating herd immunity effects into cohort models of vaccine cost-effectiveness

BACKGROUND

Cohort models are often used in cost-effectiveness analysis (CEA) of vaccination. However, because they cannot capture herd immunity effects, cohort models underestimate the reduction in incidence caused by vaccination. Dynamic models capture herd immunity effects but are often not adopted in vaccine CEA.

OBJECTIVE

The objective was to develop a pseudo-dynamic approximation that can be incorporated into an existing cohort model to capture herd immunity effects.

METHODS

The authors approximated changing force of infection due to universal vaccination for a pediatric infectious disease. The projected lifetime cases in a cohort were compared under 1) a cohort model, 2) a cohort model with pseudo-dynamic approximation, and 3) an age-structured susceptible-exposed-infectious-recovered compartmental (dynamic) model. The authors extended the methodology to sexually transmitted infections.

RESULTS

For average to high values of vaccine coverage (P > 60%) and small to average values of the basic reproduction number (R(0) < 10), which describes school-based vaccination programs for many common infections, the pseudo-dynamic approximation significantly improved projected lifetime cases and was close to projections of the full dynamic model. For large values of R(0) (R(0) > 15), projected lifetime cases were similar under the dynamic model and the cohort model, both with and without pseudo-dynamic approximation. The approximation captures changes in the mean age at infection in the 1st vaccinated cohort.

CONCLUSIONS

This methodology allows for preliminary assessment of herd immunity effects on CEA of universal vaccination for pediatric infectious diseases. The method requires simple adjustments to an existing cohort model and less data than a full dynamic model.

Age-based programs for vaccination against HPV

BACKGROUND

The risk of infection with human papillomavirus (HPV) increases with age. Answering the question of which age groups are appropriate to target for catch-up vaccination with the newly licensed quadrivalent HPV vaccine (types 6/11/16/18) will be important for developing vaccine policy recommendations.

OBJECTIVES

To assess the value of varying female HPV vaccination strategies by specific age groups of a catch-up program in the United States.

METHODS

The authors used previously published mathematical population dynamic model and cost-utility analysis to evaluate the public health impact and cost-effectiveness of alternative quadrivalent HPV (6/11/16/18) vaccination strategies. The model simulates heterosexual transmission of HPV infection and occurrence of cervical intraepithelial neoplasia (CIN), cervical cancer, and external genital warts in an age-structured population stratified by sex and sexual activity groups. The cost-utility analysis estimates the cost of vaccination, screening, diagnosis, and treatment of HPV diseases, and quality-adjusted survival.

RESULTS

Compared with the current screening practices, vaccinating girls and women ages 12 to 24 years was the most effective strategy, reducing the number of HPV6/11/16/18-related genital warts, CIN grades 2 and 3, and cervical cancer cases among women in the next 25 years by 3,049,285, 1,399,935, and 30,021; respectively. The incremental cost-effectiveness ratio of this strategy when compared with vaccinating girls and women ages 12 to 19 years was $10,986 per quality-adjusted life-year gained. CONCLUSION;: Relative to other commonly accepted health-care programs, vaccinating girls and women ages 12 to 24 years appears cost-effective.

Cost-effectiveness analysis of human papillomavirus-vaccination programs to prevent cervical cancer in Austria

OBJECTIVE

The study predicts long-term cervical cancer related population health and economic effects of introducing the HPV-vaccination for 12-year-old girls (and boys) in addition to current screening compared with screening only.

METHOD

Health effects are predicted by a dynamic transmission model. Model results are used to calculate incremental cost-effectiveness ratios (ICER) in euro per life year gained (LYG) for a time-horizon between 2008 and 2060 from a public payer and a societal perspective.

RESULTS

Vaccination of girls results a discounted ICER of euro 64,000/LYG and euro 50,000/LYG from a payer's and societal perspectives respectively. The additional vaccination of boys increases the ICER to euro 311,000 and euro 299,000/LYG respectively. Results were most sensitive to vaccination price, discount rate and time-horizon.

CONCLUSION

HPV-vaccination for girls should be cost-effective when adopting a longer time-horizon and a societal perspective. Applying a shorter time frame and a payer's perspective or vaccinating boys may not be cost-effective without reducing the vaccine price.

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.

Estimating progression rates for human papillomavirus infection from epidemiological data

A Markov model was constructed in order to estimate type-specific rates of cervical lesion progression and regression in women with high-risk human papillomavirus (HPV). The model was fitted to age- and type-specific data regarding the HPV DNA and cytological status of women undergoing cervical screening in a recent screening trial, as well as cervical cancer incidence. It incorporates different assumptions about the way lesions regress, the accuracy of cytological screening, the specificity of HPV DNA testing, and the age-specific prevalence of HPV infection. Combinations of assumptions generate 162 scenarios for squamous cell carcinomas and 54 scenarios for adenocarcinomas. Simulating an unscreened cohort of women infected with high-risk HPV indicates that the probability of an infection continuing to persist and to develop into invasive cancer depends on the length of time it has already persisted. The scenarios and parameter sets that produce the best fit to available epidemiological data provide a basis for modeling the natural history of HPV infection and disease.

New vaccines against otitis media: projected benefits and cost-effectiveness

OBJECTIVE

New vaccines that offer protection against otitis media caused by nontypeable Haemophilus influenzae and by Moraxella catarrhalis are under development. However, the potential health benefits and economic effects of such candidate vaccines have not been systematically assessed.

METHODS

We created a computerized model to compare the projected benefits and costs of (1) the currently available 7-valent pneumococcal conjugate vaccine, (2) a candidate pneumococcal-nontypeable H influenzae vaccine that has been tested in Europe, (3) a hypothetical pneumococcal-nontypeable H influenzae-Moraxella vaccine, and (4) no vaccination. The clinical probabilities of acute otitis media and of otitis media with effusion were generated from multivariate analyses of data from 2 large health maintenance organizations and from the Pittsburgh Child Development/Otitis Media Study cohort. Other probabilities, costs, and quality-of-life values were derived from published and unpublished sources. The base-case analysis assumed vaccine dose costs of $65 for the 7-valent pneumococcal conjugate vaccine, $100 for the pneumococcal-nontypeable H influenzae vaccine, and $125 for the pneumococcal-nontypeable H influenzae-Moraxella vaccine.

RESULTS

With no vaccination, we projected that 13.7 million episodes of acute otitis media would occur annually in US children aged 0 to 4 years, at an annual cost of $3.8 billion. The 7-valent pneumococcal conjugate vaccine was projected to prevent 878,000 acute otitis media episodes, or 6.4% of those that would occur with no vaccination; the corresponding value for the pneumococcal-nontypeable H influenzae vaccine was 3.7 million (27%) and for the pneumococcal-nontypeable H influenzae-Moraxella vaccine was 4.2 million (31%). Using the base-case vaccine costs, pneumococcal-nontypeable H influenzae vaccine use would result in net savings compared with nontypeable 7-valent pneumococcal conjugate use. Conversely, pneumococcal-nontypeable H influenzae-Moraxella vaccine use would not result in savings compared with pneumococcal-nontypeable H influenzae vaccine use, but would cost $48 000 more per quality-adjusted life-year saved. The results were sensitive to variations in assumptions on vaccine effectiveness and vaccine dose costs but not to variations in other assumptions.

CONCLUSIONS

New candidate vaccines against otitis media have the potential to prevent millions of disease episodes in the United States annually. If priced comparably with other recently introduced vaccines, these new otitis vaccines could achieve cost-effectiveness comparable with or more favorable than that of the 7-valent pneumococcal conjugate vaccine.

The health and economic impact of cervical cancer screening and human papillomavirus vaccination in kidney transplant recipients

BACKGROUND

The risk of cervical cancer in women who are kidney transplant recipients is increased, but little is known about the effectiveness of screening and human papillomavirus (HPV) vaccination in this group of women. We sought to determine the cost effectiveness of annual screening for cervical cancers using conventional cytology, liquid-based cytology (LBC), and pretransplant HPV vaccination in kidney transplant recipients.

METHODS

Three deterministic Markov models were developed to compare the costs and health outcomes in a cohort of women (n=1000) with kidney transplants aged 18 to 69 who underwent annual screening using conventional cytology, LBC, and HPV vaccination in HPV naïve women.

RESULTS

After a screening period of 50 years, the incremental benefits of screening using conventional cytology compared with no screening were 0.05 life years saved (LYS) (18.2 days of lives saved), the incremental costs were $608, giving an incremental cost-effectiveness ratio of $12,160 per LYS. Compared with conventional cytology alone, the incremental cost-effectiveness ratios of annual screening using LBC and HPV vaccination before transplantation (assuming nonwaning efficacy) were $127,000 and $152,333 per LYS, respectively.

CONCLUSION

The recommended policy of annual screening using conventional cytology is cost effective. The replacement of conventional cytology with LBC is likely to provide minimal survival benefits but considerable costs. Assuming the reported trial-based vaccine efficacy in HPV naïve women, a program of HPV vaccination before kidney transplantation is unlikely to be cost effective. Additional data about the long-term efficacy and safety of HPV vaccination is required before it should be included as standard care of renal transplant recipients.

Development and evaluation of a PCR and mass spectroscopy (PCR-MS)-based method for quantitative, type-specific detection of human papillomavirus

Knowledge of the central role of high-risk human papillomavirus (HPV) in cervical carcinogenesis, coupled with an emerging need to monitor the efficacy of newly introduced HPV vaccines, warrant development and evaluation of type-specific, quantitative HPV detection methods. In the present study, a prototype PCR and mass spectroscopy (PCR-MS)-based method to detect and quantitate 13 high-risk HPV types is compared to the Hybrid Capture 2 High-Risk HPV DNA test (HC2; Digene Corp., Gaithersburg, MD) in 199 cervical scraping samples and to DNA sequencing in 77 cervical tumor samples. High-risk HPV types were detected in 76/77 (98.7%) cervical tumor samples by PCR-MS. Degenerate and type-specific sequencing confirmed the types detected by PCR-MS. In 199 cervical scraping samples, all 13 HPV types were detected by PCR-MS. Eighteen (14.5%) of 124 cervical scraping samples that were positive for high-risk HPV by HC2 were negative by PCR-MS. In all these cases, degenerate DNA sequencing failed to detect any of the 13 high-risk HPV types. Nearly half (46.7%) of the 75 cervical scraping samples that were negative for high-risk HPV by the HC2 assay were positive by PCR-MS. Type-specific sequencing in a subset of these samples confirmed the HPV type detected by PCR-MS. Quantitative PCR-MS results demonstrated that 11/75 (14.7%) samples contained as much HPV copies/cell as HC2-positive samples. These findings suggest that this prototype PCR-MS assay performs at least as well as HC2 for HPV detection, while offering the additional, unique advantages of type-specific identification and quantitation. Further validation work is underway to define clinically meaningful HPV detection thresholds and to evaluate the potential clinical application of future generations of the PCR-MS assay.

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.

Human papillomavirus genotype distributions: implications for vaccination and cancer screening in the United States

BACKGROUND

Limited data are available describing human papillomavirus (HPV) genotype distributions in cervical cancer in the United States. Such studies are needed to predict how HPV vaccination and HPV-based screening will influence cervical cancer prevention.

METHODS

We used the New Mexico Surveillance, Epidemiology, and End Results Registry to ascertain cases of in situ (n = 1213) and invasive (n = 808) cervical cancer diagnosed during 1985-1999 and 1980-1999, respectively, in the state of New Mexico. HPV genotyping was performed using two polymerase chain reaction-based methods on paraffin-embedded tissues from in situ and invasive cancers and on cervical Papanicolaou test specimen from control subjects (ie, women aged 18-40 years attending clinics for routine cervical screening [n = 4007]). Relative risks for cervical cancer were estimated, and factors associated with age at cancer diagnosis and the prevalence of HPV genotypes in cancers were examined.

RESULTS

The most common HPV genotypes detected in invasive cancers were HPV type 16 (HPV16, 53.2%), HPV18 (13.1%), and HPV45 (6.1%) and those in in situ cancers were HPV16 (56.3%), HPV31 (12.6%), and HPV33 (8.0%). Invasive cancer case subjects who were positive for HPV16 or 18 were diagnosed at younger ages than those who were positive for other carcinogenic HPV genotypes (mean age at diagnosis: 48.1 [95% confidence interval {CI} = 46.6 to 49.6 years], 45.9 [95% CI = 42.9 to 49.0 years], and 52.3 years [95% CI = 50.0 to 54.6 years], respectively). The proportion of HPV16-positive in situ and invasive cancers, but not of HPV18-positive cancers, declined with more recent calendar year of diagnosis, whereas the proportion positive for carcinogenic HPV genotypes other than HPV18 increased.

CONCLUSIONS

HPV16 and 18 caused the majority of invasive cervical cancer in this population sample of US women, but the proportion attributable to HPV16 declined over the last 20 years. The age at diagnosis of HPV16- and HPV18-related cancers was 5 years earlier than that of cancers caused by carcinogenic HPV genotypes other than HPV16 and 18, suggesting that the age at initiation of cervical screening could be delayed in HPV-vaccinated populations.

Human Papillomavirus Quadrivalent Vaccine: A Look Behind The Numbers

The human papillomavirus (HPV) quadrivalent vaocine was licensed in 2006 for prevention of cervical, vulvar, and vaginal cancers caused by HPV-16 and −18 and genital warts caused by HPV-6 and −11. It is also indicated for prevention of precancerous and dysplastic lesions caused by HPV-6, −11, −16, and −18. Questions exist about the number of women and girls infected with the HPV strains covered by the vaccine, as well as about the vaccine's cost-effectiveness. There are also concerns about the efficacy of the vaccine in girls and young women, the population impact of the vaccine, the duration of protection, and the usefulness of the vaccine in developing countries. Careful consideration should be given to these issues by pharmacy and pharmacy professional organizations. To formulate reasonable healthcare guidelines, pharmacists and other healthcare professionals will need to engage policymakers in conversations concerning the vaccine's merits or limitations and the economic impact.

Natural history of human papillomavirus infections, cytologic and histologic abnormalities, and cancer

Over 100 human papillomavirus (HPV) types have been identified to date, of which over 40 infect the genital tract, primarily through sexual transmission. The many different genital HPV types appear to infect, resolve, or persist, and cause abnormal cytology and cervical intraepithelial neoplasia. Several cofactors have been associated with HPV persistence and lesion progression, including smoking, long-term oral contraceptive use, other sexually transmitted infections, host immunogenetics, and viral factors, such as HPV type and HPV variants. Given the discovery of HPV as the single primary cause of invasive cervical cancer, primary and secondary interventions have been realized, including HPV testing in cervical screening programs and prophylactic HPV vaccines. Because first generation HPV vaccines only target the two most common HPV types found in cervical cancer (HPV 16 and 18), cervical screening programs must continue, and the relative roles of HPV vaccination in young women and HPV testing in older women (alone or in conjunction with cytology) will be determined over the next decades.