Assessing cost-effectiveness of HPV vaccines with decision analytic models: what are the distinct challenges of low- and middle-income countries? A protocol for a systematic review

Factors Influencing the Cost-Effectiveness Outcomes of HPV Vaccination and Screening Interventions in Low-to-Middle-Income Countries (LMICs): A Systematic Review

BACKGROUND

Cervical cancer ranks fourth amongst the commonest malignancies worldwide and the second most prevalent cancer afflicting women in low-to-middle income countries (LMICs), hence, of great public health importance. LMICs are the most affected regions as evidenced by their high prevalence of the disease. Mortality associated with cervical neoplasms is preventable through the implementation of recommended preventive approaches.

AIMS

This review aimed to appraise evidence on the cost effectiveness of cervical cancer prevention interventions in LMICs involving cervical screening and human papilloma virus (HPV) vaccination programmes.

METHODS

A search of CINAHL, MEDLINE, PubMed, and Web of Science was elicited and studies published between 1st January 2008 and 31st December 2018 were retrieved. Two authors independently undertook the screening, review, selection of studies, and data extraction with disagreements being resolved through discussion and consensus.

RESULTS

Twelve studies were selected. The cost-effectiveness outcomes of HPV vaccination and screening interventions are dependent on age, screening method used, intervention coverage, and the number of doses or visits required for vaccination and screening, respectively. A combination of visual inspection with acetic acid (VIA) screening and HPV vaccination appears to be the most cost-effective approach in reducing the lifetime risk for HPV-linked cervical neoplasms. Similarly, vaccination as a stand-alone intervention is potentially cost effective provided the coverage is maintained between 70 and 100%.

CONCLUSIONS

HPV vaccination and screening interventions may be cost effective in LMICs and potentially reduce the lifetime risk, economic burden, and associated mortality. However, it is important to consider the factors that influence the cost effectiveness of cervical cancer prevention interventions for better outcomes to be realised.

Cost effectiveness of human papilloma virus vaccination in low and middle income countries: a systematic review of literature

INTRODUCTION

Low and middle income countries (LMICs) bear more than 50% of the current cervical cancer burden over the last decade with linkages to lack of HPV vaccination, high levels of poverty, illiteracy and nonexistent or poor screening programs. Governments of LMICs need enough convincing evidence that HPV vaccination will be more cost-effective in reducing the scourge of cervical cancer.

AREAS COVERED

A systematic review to identify suitable studies from MEDLINE(via PubMed), EMBASE and Electronic search through GOOGLE for original and review articles from 2007 to 2014 on cost-effectiveness of human papilloma virus vaccination of pre-adolescent girls in LMICs was conducted. A total of 19 full articles were finally selected and reviewed after screening out those not consistent with the inclusion and exclusion criteria.

EXPERT COMMENTARY

Most studies on cost-effectiveness of HPV vaccine in LMICs show that lowering cost of HPV vaccination with or without Pap smear screening is cost-effective in areas with high incidence of cervical cancer.

Inclusion of the value of herd immunity in economic evaluations of vaccines. A systematic review of methods used

OBJECTIVE

The objectives of this review were to identify vaccine economic evaluations that include herd immunity and describe the methodological approaches used.

METHODS

We used Kim and Goldie's search strategy from a systematic review (1976-2007) of modelling approaches used in vaccine economic evaluations and additionally searched PubMed/MEDLINE and Embase for 2007-2015. Studies were classified according to modelling approach used. Methods for estimating herd immunity effects were described, in particular for the static models.

RESULTS

We identified 625 economic evaluations of vaccines against human-transmissible diseases from 1976 to 2015. Of these, 172 (28%) included herd immunity. While 4% of studies included herd immunity in 2001, 53% of those published in 2015 did this. Pneumococcal, human papilloma and rotavirus vaccines represented the majority of studies (63%) considering herd immunity. Ninety-five of the 172 studies utilised a static model, 59 applied a dynamic model, eight a hybrid model and ten did not clearly state which method was used. Relatively crude methods and assumptions were used in the majority of the static model studies.

CONCLUSION

The proportion of economic evaluations using a dynamic model has increased in recent years. However, 55% of the included studies used a static model for estimating herd immunity. Values from a static model can only be considered reliable if high quality surveillance data are incorporated into the analysis. Without this, the results are questionable and they should only be included in sensitivity analysis.

Challenges in Cost-Effectiveness Analysis Modelling of HPV Vaccines in Low- and Middle-Income Countries: A Systematic Review and Practice Recommendations

BACKGROUND

Low- and middle-income countries (LMICs) face a number of challenges in implementing cervical cancer prevention programmes that do not apply in high-income countries.

OBJECTIVE

This review assessed how context-specific challenges of implementing cervical cancer prevention strategies in LMICs were accounted for in existing cost-effectiveness analysis (CEA) models of human papillomavirus (HPV) vaccination.

METHODS

The databases of MEDLINE, EMBASE, NHS Economic Evaluation Database, EconLit, Web of Science, and the Center for the Evaluation of Value and Risk in Health (CEA) Registry were searched for studies published from 2006 to 2015. A descriptive, narrative, and interpretative synthesis of data was undertaken.

RESULTS

Of the 33 studies included in the review, the majority acknowledged cost per vaccinated girl (CVG) (26 studies) and vaccine coverage rate (21 studies) as particular challenges for LMICs, while nine studies identified screening coverage rate as a challenge. Most of the studies estimated CVG as a composite of different cost items. However, the basis for the items within this composite cost was unclear. The majority used an assumption rather than an observed rate to represent screening and vaccination coverage rates. CVG, vaccine coverage and screening coverage were shown by some studies through sensitivity analyses to reverse the conclusions regarding cost-effectiveness, thereby significantly affecting policy recommendations.

CONCLUSIONS

While many studies recognized aspects of the particular challenges of HPV vaccination in LMICs, greater efforts need to be made in adapting models to account for these challenges. These include adapting costings of HPV vaccine delivery from other countries, learning from the outcomes of cervical cancer screening programmes in the same geographical region, and taking into account the country's previous experience with other vaccination programmes.