Model Comparisons of the Effectiveness and Cost-Effectiveness of Vaccination: A Systematic Review of the Literature

OBJECTIVES

To describe all published articles that have conducted comparisons of model-based effectiveness and cost-effectiveness results in the field of vaccination. Specific objectives were to 1) describe the methodologies used and 2) identify the strengths and limitations of the studies.

METHODS

We systematically searched MEDLINE and Embase databases for studies that compared predictions of effectiveness and cost-effectiveness of vaccination of two or more mathematical models. We categorized studies into two groups on the basis of their data source for comparison (previously published results or new simulation results) and performed a qualitative synthesis of study conclusions.

RESULTS

We identified 115 eligible articles (only 5% generated new simulations from the reviewed models) examining the effectiveness and cost-effectiveness of vaccination against 14 pathogens (69% of studies examined human papillomavirus, influenza, and/or pneumococcal vaccines). The goal of most of studies was to summarize evidence for vaccination policy decisions, and cost-effectiveness was the most frequent outcome examined. Only 33%, 25%, and 3% of studies followed a systematic approach to identify eligible studies, assessed the quality of studies, and performed a quantitative synthesis of results, respectively. A greater proportion of model comparisons using published studies followed a systematic approach to identify eligible studies and to assess their quality, whereas more studies using new simulations performed quantitative synthesis of results and identified drivers of model conclusions. Most comparative modeling studies concluded that vaccination was cost-effective.

CONCLUSIONS

Given the variability in methods used to conduct/report comparative modeling studies, guidelines are required to enhance their quality and transparency and to provide better tools for decision making.

Economic Evaluation and Budget Impact Analysis of Vaccination against Haemophilus influenzae Type b Infection in Thailand

Current study aimed to estimate clinical and economic outcomes of providing the Haemophilus influenzae type b (Hib) vaccination as a national vaccine immunization program in Thailand. A decision tree combined with Markov model was developed to simulate relevant costs and health outcomes covering lifetime horizon in societal and health care payer perspectives. This analysis considered children aged under 5 years old whom preventive vaccine of Hib infection are indicated. Two combined Hib vaccination schedules were considered: three-dose series (3 + 0) and three-dose series plus a booster does (3 + 1) compared with no vaccination. Budget impact analysis was also performed under Thai government perspective. The outcomes were reported as Hib-infected cases averted and incremental cost-effectiveness ratios (ICERs) in 2014 Thai baht (THB) ($) per quality-adjusted life year (QALY) gained. In base-case scenario, the model estimates that 3,960 infected cases, 59 disability cases, and 97 deaths can be prevented by national Hib vaccination program. The ICER for 3 + 0 schedule was THB 1,099 ($34) per QALY gained under societal perspective. The model was sensitive to pneumonia incidence among aged under 5 years old and direct non-medical care cost per episode of Hib pneumonia. Hib vaccination is very cost-effective in the Thai context. The budget impact analysis showed that Thai government needed to invest an additional budget of 110 ($3.4) million to implement Hib vaccination program. Policy makers should consider our findings for adopting this vaccine into national immunization program.

Economic evaluations of Haemophilus influenzae type b (Hib) vaccine: a systematic review

AIMS

The World Health Organization (WHO) recommends the use of Haemophilus influenzae type b (Hib) conjugate vaccines, but China and Thailand have not used Hib vaccination in their national immunization programs. This systematic review aimed to update published economic evaluations of Hib vaccinations and to determine factors that potentially affected their cost-effectiveness.

METHODS

Searches were performed from the inception until December 2015 using 13 databases: CAB direct; CEA registry; EconLit; EMBASE; E-library; NHSEED; PAHO; POPLINE; PubMed; Redalyc project; RePEc; SciELO; and WHOLIS. Reference lists of relevant studies and grey literature were also searched. Full economic evaluations of Hib vaccination with results of costs and outcomes were included. The WHO checklist was used to evaluate the quality of the included studies. Data from eligible studies were extracted using a standardized data collection form.

RESULTS

Out of 830 articles, 27 were included. Almost half of the studies (12/27) were conducted in high-income countries. Twelve studies (12/27) investigated the Hib vaccine as an addition to the existing vaccination program. Most studies (17/27) examined a 3-dose schedule of Hib vaccine. Nineteen studies (19/27) reported the model used, where all were decision tree models. Most of the studies (23/27) demonstrated an economic value of Hib vaccination programs, key influential parameters being incidence rates of Hib disease and vaccine price.

CONCLUSIONS

Hib vaccination programs are mostly found to be cost-effective across geographic regions and country income levels, and Hib vaccination is recommended for inclusion into all national immunization programs. The findings are expected to support policy-makers for making decisions on allocating limited resources of the Hib vaccination program effectively.

A Systematic Review of Economic Evaluation Methodologies Between Resource-Limited and Resource-Rich Countries: A Case of Rotavirus Vaccines

BACKGROUND

For more than three decades, the number and influence of economic evaluations of healthcare interventions have been increasing and gaining attention from a policy level. However, concerns about the credibility of these studies exist, particularly in studies from low- and middle- income countries (LMICs). This analysis was performed to explore economic evaluations conducted in LMICs in terms of methodological variations, quality of reporting and evidence used for the analyses. These results were compared with those studies conducted in high-income countries (HICs).

METHODS

Rotavirus vaccine was selected as a case study, as it is one of the interventions that many studies in both settings have explored. The search to identify individual studies on rotavirus vaccines was performed in March 2014 using MEDLINE and the National Health Service Economic Evaluation Database. Only full economic evaluations, comparing cost and outcomes of at least two alternatives, were included for review. Selected criteria were applied to assess methodological variation, quality of reporting and quality of evidence used.

RESULTS

Eighty-five studies were included, consisting of 45 studies in HICs and 40 studies in LMICs. Seventy-five percent of the studies in LMICs were published by researchers from HICs. Compared with studies in HICs, the LMIC studies showed less methodological variety. In terms of the quality of reporting, LMICs had a high adherence to technical criteria, but HICs ultimately proved to be better. The same trend applied for the quality of evidence used.

CONCLUSION

Although the quality of economic evaluations in LMICs was not as high as those from HICs, it is of an acceptable level given several limitations that exist in these settings. However, the results of this study may not reflect the fact that LMICs have developed a better research capacity in the domain of health economics, given that most of the studies were in theory led by researchers from HICs. Putting more effort into fostering the development of both research infrastructure and capacity building as well as encouraging local engagement in LMICs is thus necessary.

Income Elasticity of Vaccines Spending versus General Healthcare Spending

Using cross-country data on gross domestic product and national expenditure on vaccines, we estimate and compare the income elasticity of vaccine expenditure and general curative healthcare expenditure. This study provides the first evidence on the national income elasticity of vaccination spending. Both fixed and random effects models are applied to data from 84 countries from 2010 to 2011. The income elasticities for healthcare expenditure and vaccine expenditure are 0.844 and 0.336, respectively. Despite vaccines' high cost-effectiveness, the national propensity to spend income on vaccines as income increases lags behind general health care. The low income elasticity of vaccine spending means that relying on economic growth alone will provide an unacceptably slow trajectory to achieving high vaccine coverage levels. Copyright © 2015 John Wiley & Sons, Ltd.

Methodological Challenges to Economic Evaluations of Vaccines: Is a Common Approach Still Possible?

Economic evaluation of vaccination is a key tool to inform effective spending on vaccines. However, many evaluations have been criticised for failing to capture features of vaccines which are relevant to decision makers. These include broader societal benefits (such as improved educational achievement, economic growth and political stability), reduced health disparities, medical innovation, reduced hospital beds pressures, greater peace of mind and synergies in economic benefits with non-vaccine interventions. Also, the fiscal implications of vaccination programmes are not always made explicit. Alternative methodological frameworks have been proposed to better capture these benefits. However, any broadening of the methodology for economic evaluation must also involve evaluations of non-vaccine interventions, and hence may not always benefit vaccines given a fixed health-care budget. The scope of an economic evaluation must consider the budget from which vaccines are funded, and the decision-maker's stated aims for that spending to achieve.

Post-GAVI sustainability of the Haemophilus influenzae type b vaccine program: The potential role of economic evaluation

Haemophilus influenzae type b (Hib) can cause severe invasive diseases which are, however, preventable by vaccination. To increase access to Hib vaccine, GAVI – the Vaccine Alliance – has provided financial support for 73 lower income countries worldwide. At the same time, GAVI has been implementing its co-financing policy, requiring recipient countries to pay a portion of vaccine costs and to increase this amount over time. Starting in 2016, 5 countries will stop receiving GAVI funding and procure the vaccine themselves. Although the graduating countries have access to the UNICEF/GAVI tendered vaccine price for 5 more years, the uncertainty in market vaccine price may hamper the post-GAVI program sustainability. A possible increase in vaccine price would cause a significant burden on governmental budgets, discouraging countries to continue the program. As a special tool, economic evaluation (EE) can assist decision makers by identifying the maximum affordable vaccine price for countries to pay. Given that only 6 GAVI-eligible countries have such analyses published, more EEs are necessary to strengthen countries' commitment during this transition period. The information will also be useful for manufacturers to determine their pricing policy.

Comparison of Economic Evaluation Methods Across Low-income, Middle-income and High-income Countries: What are the Differences and Why?

There are marked differences in methods used for undertaking economic evaluations across low-income, middle-income, and high-income countries. We outline the most apparent dissimilarities and reflect on their underlying reasons. We randomly sampled 50 studies from each of three country income groups from a comprehensive database of 2844 economic evaluations published between January 2012 and May 2014. Data were extracted on ten methodological areas: (i) availability of guidelines; (ii) research questions; (iii) perspective; (iv) cost data collection methods; (v) cost data analysis; (vi) outcome measures; (vii) modelling techniques; (viii) cost-effectiveness thresholds; (ix) uncertainty analysis; and (x) applicability. Comparisons were made across income groups and odds ratios calculated. Contextual heterogeneity rightly drives some of the differences identified. Other differences appear less warranted and may be attributed to variation in government health sector capacity, in health economics research capacity and in expectations of funders, journals and peer reviewers. By highlighting these differences, we seek to start a debate about the underlying reasons why they have occurred and to what extent the differences are conducive for methodological advancements. We suggest a number of specific areas in which researchers working in countries of differing environments could learn from one another.

Economic Evaluation in Global Perspective: A Bibliometric Analysis of the Recent Literature

We present a bibliometric analysis of recently published full economic evaluations of health interventions and reflect critically on the implications of our findings for this growing field. We created a database drawing on 14 health, economic, and/or general literature databases for articles published between 1 January 2012 and 3 May 2014 and identified 2844 economic evaluations meeting our criteria. We present findings regarding the sensitivity, specificity, and added value of searches in the different databases. We examine the distribution of publications between countries, regions, and health areas studied and compare the relative volume of research with disease burden. We analyse authors' country and institutional affiliations, journals and journal type, language, and type of economic evaluation conducted. More than 1200 economic evaluations were published annually, of which 4% addressed low-income countries, 4% lower-middle-income countries, 14% upper-middle-income countries, and 83% high-income countries. Across country income levels, 53, 54, 86, and 100% of articles, respectively, included an author based in a country within the income level studied. Biomedical journals published 74% of economic evaluations. The volume of research across health areas correlates more closely with disease burden in high-income than in low-income and middle-income countries. Our findings provide an empirical basis for further study on methods, research prioritization, and capacity development in health economic evaluation.

Can a Compact Pre-Filled Auto-Disable Injection System (cPAD) Save Costs for DTP-HepB-Hib Vaccine as Compared with Single-Dose (SDV) and Multi-Dose Vials (MDV)? Evidence from Cambodia, Ghana, and Peru

Background

A compact pre-filled auto-disable injection (cPAD) presentation is being developed for the fully liquid pentavalent DTP-HepB-Hib vaccine. A cost analysis (CA) to compare this presentation with the presently used single-dose vial (SDV) and multi-dose vial (MDV) was conducted in Cambodia, Ghana, and Peru.

Methodology

The CA included the development of an excel-based costing model and considered the costs of vaccine, safe injection equipment, procurement, storage, transport and distribution, vaccine administration by health staff, medical waste management, start-up activities, as well as coverage, birth cohort, vaccine, and safe injection equipment wastage rates. The outcome was the change in cost per pentavalent fully immunized child (PFIC) for a switch to cPAD. Field visits to health facilities, and interviews with key informants from immunization services and regulatory authorities, were conducted to collect data and to test the costing model in country context. Cost data were also obtained from manufacturers, published price lists, and author estimates. A sensitivity analysis (SA) was conducted to explore possible variations in values of data collected.

Results

Based on vaccine price trends estimated for 2016, cPAD is less costly in Ghana [incremental cost per PFIC: $US−0.59 (−6.46 %)] than the current presentation (ten-dose MDV) and in Peru (SDV): $US−0.89 (−7.14 %). In Cambodia, cPAD is more costly than SDV: $US+0.33 (+3.90 %).

Discussion and Conclusion

The most significant cost item per PFIC is the vaccine (reflecting wastage rates) in all presentations. The dominance of the vaccine price per dose and, to a lesser extent, the wastage rates in the incremental cost per PFIC show potential to simplify future analyses. Other relevant considerations at country level for a change of presentation include the potential for improved safety with cPAD, planned introduction of other vaccines, environmental and safety issues, and financial sustainability.

Electronic supplementary material

The online version of this article (doi:10.1007/s40801-015-0010-0) contains supplementary material, which is available to authorized users.

Methodological reviews of economic evaluations in health care: what do they target?

INTRODUCTION AND OBJECTIVES

An increasing number of published studies of economic evaluations of health technologies have been reviewed and summarized with different purposes, among them to facilitate decision-making processes. These reviews have covered different aspects of economic evaluations, using a variety of methodological approaches. The aim of this study is to analyze the methodological characteristics of the reviews of economic evaluations in health care, published during the period 1990-2010, to identify their main features and the potential missing elements. This may help to develop a common procedure for elaborating these kinds of reviews.

METHODS

We performed systematic searches in electronic databases (Scopus, Medline and PubMed) of methodological reviews published in English, period 1990-2010. We selected the articles whose main purpose was to review and assess the methodology applied in the economic evaluation studies. We classified the data according to the study objectives, period of the review, number of reviewed studies, methodological and non-methodological items assessed, medical specialty, type of disease and technology, databases used for the review and their main conclusions. We performed a descriptive statistical analysis and checked how generalizability issues were considered in the reviews.

RESULTS

We identified 76 methodological reviews, 42 published in the period 1990-2001 and 34 during 2002-2010. The items assessed most frequently (by 70% of the reviews) were perspective, type of economic study, uncertainty and discounting. The reviews also described the type of intervention and disease, funding sources, country in which the evaluation took place, type of journal and author's characteristics. Regarding the intertemporal comparison, higher frequencies were found in the second period for two key methodological items: the source of effectiveness data and the models used in the studies. However, the generalizability issues that apparently are creating a growing interest in the economic evaluation literature did not receive as much attention in the reviews of the second period. The remaining items showed similar frequencies in both periods.

CONCLUSIONS

Increasingly more reviews of economic evaluation studies aim to analyze the application of methodological principles, and offer summaries of papers classified by either diseases or health technologies. These reviews are useful for finding literature trends, aims of studies and possible deficiencies in the implementation of methods of specific health interventions. As no significant methodological improvement was clearly detected in the two periods analyzed, it would be convenient to pay more attention to the methodological aspects of the reviews.

Cost-effectiveness of Haemophilus influenzae type b conjugate vaccine in low- and middle-income countries: regional analysis and assessment of major determinants

OBJECTIVES

To estimate the cost-effectiveness of Haemophilus influenzae type b (Hib) conjugate vaccine in low- and middle-income countries and identify the model variables, which are most important for the result.

STUDY DESIGN

A static decision tree model was developed to predict incremental costs and health impacts. Estimates were generated for 4 country groups: countries eligible for funding by the GAVI Alliance in Africa and Asia, lower middle-income countries, and upper middle-income countries. Values, including disease incidence, case fatality rates, and treatment costs, were based on international country estimates and the scientific literature.

RESULTS

From the societal perspective, it is estimated that the probability of Hib conjugate vaccine cost saving is 34%-53% in Global Alliance for Vaccines and Immunization eligible African and Asian countries, respectively. In middle-income countries, costs per discounted disability adjusted life year averted are between US$37 and US$733. Variation in vaccine prices and risks of meningitis sequelae and mortality explain most of the difference in results. For all country groups, disease incidence cause the largest part of the uncertainty in the result.

CONCLUSIONS

Hib conjugate vaccine is cost saving or highly cost-effective in low- and middle-income settings. This conclusion is especially influenced by the recent decline in Hib conjugate vaccine prices and new data revealing the high costs of lost productivity associated with meningitis sequelae.

Delivering vaccines for the prevention of pneumonia - programmatic and financial issues

Pneumonia is the leading cause of morbidity and mortality in children younger than 5 years. Vaccines are available against the main bacterial pathogens Haemophilus influenzae type b and Streptococcus pneumoniae. There are also vaccines against measles and pertussis; diseases that can predispose a child to pneumonia. Partners such as the Global Alliance for Vaccines and Immunisation (GAVI), the Hib Initiative, the Accelerated Development and Introduction Plan for pneumococcal vaccines and the Measles Initiative, have accelerated the introduction of vaccines into developing countries. Whilst significant improvements in vaccine coverage have occurred globally over the past decade, there still remains an urgent need to scale-up key pneumonia protection and treatment interventions as identified in the Global Action Plan for the Prevention and Control of Pneumonia (GAPP). There is promise that global immunisation will continue to improve child survival. However, there are several challenges to vaccine implementation that must first be addressed, including: a lack of access to under-served and marginalised populations; inadequate planning and management; a lack of political commitment; weak monitoring and surveillance programmes and assured sustainable finance and supply of quality vaccines. There is an urgent need to increase global awareness of the devastation that pneumonia brings to the worlds poorest communities.

Costs of meningitis sequelae in children in Dakar, Senegal

BACKGROUND

Survivors of bacterial meningitis risk lifelong sequelae. In economic evaluations of vaccines protecting against meningitis, treatment and productivity costs due to meningitis sequelae are rarely included in studies from low-income countries, mainly due to lack of data. The aim of this study was to estimate the costs of meningitis sequelae in children in Senegal from the perspective of households.

METHODS

Children who had suffered from bacterial meningitis were identified from a database at Albert Royer Hospital in Dakar. Sixty-eight children were located at their home and caregivers interviewed about costs during the acute meningitis episode and due to meningitis sequelae, including productivity loss from caring for a disabled child. Lifetime costs were predicted by assuming a life expectancy of 30 years for disabled children.

RESULTS

Seventy-one percent of the children had either minor or major sequelae. Mean discounted lifetime sequelae costs amounted to US$ 34,895 (95% confidence interval: US$ 67-96,755) per child. Discounted childcare costs amounted to US$ 3158 (9%), treatment costs US$ 460 (1%) and productivity costs US$ 31,276 (90%). No children were receiving rehabilitation services by the time the study was conducted.

CONCLUSION

The present study is the first to present data on household costs from families with disabled children in a low-income country setting. Caring for a disabled child is a considerable financial as well as emotional burden for the individual family. None of the families could afford the treatment they desired for their child.

Dose-specific efficacy of Haemophilus influenzae type b conjugate vaccines: a systematic review and meta-analysis of controlled clinical trials

Global coverage of infant Haemophilus influenzae type b (Hib) vaccination has increased considerably during the past decade, partly due to GAVI Alliance donations of the vaccine to low-income countries. In settings where large numbers of children receive only one or two vaccine doses rather than the recommended three doses, dose-specific efficacy estimates are needed to predict impact. The objective of this meta-analysis is to determine Hib vaccine efficacy against different clinical outcomes after receiving one, two or three doses of vaccine. Studies were eligible for inclusion if a prospective, controlled design had been used to evaluate commercially available Hib conjugate vaccines. Eight studies were included. Pooled vaccine efficacies against invasive Hib disease after one, two or three doses of vaccine were 59%, 92% and 93%, respectively. The meta-analysis provides robust estimates for use in decision-analytical models designed to predict the impact of Hib vaccine.

Accelerating introduction of new vaccines: barriers to introduction and lessons learned from the recent Haemophilus influenzae type B vaccine experience

Adoption of new vaccines in developing countries is critical to reducing child mortality and meeting Millennium Development Goal 4. However, such introduction has historically suffered from significant delays that can be attributed to various factors including (i) lack of recognition of the value of a vaccine, (ii) factors related to weak health systems, and (iii) policy considerations. Recently, the Global Alliance for Vaccines and Immunization (GAVI) supported efforts to accelerate the introduction of Haemophilus influenzae type b (Hib) vaccines in developing countries, which resulted in a significant surge in vaccine adoption by these countries. The experience with Hib vaccines, as well as similar efforts by GAVI to support the introduction of new pneumococcal and rotavirus vaccines, provides a strategy for new vaccine adoption that is reviewed in this paper, providing a useful model to help accelerate the uptake of other life-saving vaccines. This strategy addresses barriers for vaccine adoption by focusing on three major areas: (i) communications to increase awareness about the various factors needed for evidence-based decisions that meet a country's health goals; (ii) research activities to answer key questions that support vaccine introduction and long-term programme sustainability; and (iii) coordination with the various stakeholders at global, regional and country levels to ensure successful programme implementation.

During the 'decade of vaccines,' the lives of 6.4 million children valued at $231 billion could be saved

Governments constantly face the challenge of determining how much they should spend to prevent premature deaths and suffering in their populations. In this article we explore the benefits of expanding the delivery of life-saving vaccines in seventy-two low- and middle-income countries, which we estimate would prevent the deaths of 6.4 million children between 2011 and 2020. We present the economic benefits of vaccines by using a "value of statistical life" approach, which is based on individuals' perceptions regarding the trade-off between income and increased risk of mortality. Our analysis shows that the vaccine expansion described above corresponds to $231 billion (uncertainty range: $116-$614 billion) in the value of statistical lives saved. This analysis complements results from analyses based on other techniques and is the first of its kind for immunizations in the world's poorest countries. It highlights the major economic benefits made possible by improving vaccine coverage.

Comparative economic evaluation of Haemophilus influenzae type b vaccination in Belarus and Uzbekistan

BACKGROUND

Hib vaccine has gradually been introduced into more and more countries during the past two decades, partly due to GAVI Alliance support to low-income countries. However, since Hib disease burden is difficult to establish in settings with limited diagnostic capacities and since the vaccine continues to be relatively expensive, some Governments remain doubtful about its value leading to concerns about financial sustainability. Similarly, several middle-income countries have not introduced the vaccine. The aim of this study is to estimate and compare the cost-effectiveness of Hib vaccination in a country relying on self-financing (Belarus) and a country eligible for GAVI Alliance support (Uzbekistan).

METHODS AND FINDINGS

A decision analytic model was used to estimate morbidity and mortality from Hib meningitis, Hib pneumonia and other types of Hib disease with and without the vaccine. Treatment costs were attached to each disease event. Data on disease incidence, case fatality ratios and costs were primarily determined from national sources. For the Belarus 2009 birth cohort, Hib vaccine is estimated to prevent 467 invasive disease cases, 4 cases of meningitis sequelae, and 3 deaths, while in Uzbekistan 3,069 invasive cases, 34 sequelae cases and 341 deaths are prevented. Estimated costs per discounted DALY averted are US$ 9,323 in Belarus and US$ 267 in Uzbekistan.

CONCLUSION

The primary reason why the cost-effectiveness values are more favourable in Uzbekistan than in Belarus is that relatively more deaths are averted in Uzbekistan due to higher baseline mortality burden. Two other explanations are that the vaccine price is lower in Uzbekistan and that Uzbekistan uses a three dose schedule compared to four doses in Belarus. However, when seen in the context of the relative ability to pay for public health, the vaccine can be considered cost-effective in both countries.