These studies typically employ decision analytic models as many of the relevant outcomes will occur over periods too long to practically assess within trials. Cost-effectiveness analysis of HPV vaccination for low and middle income countries (LMICs) often use and adapt decision analytic models employed by studies conducted in high income countries.
However, challenges encountered by LMICs in implementing and maintaining a comprehensive cervical cancer prevention strategy make it difficult to anticipate what programme coverage rates and cost of vaccination might be realised. Both are crucial parameters in most decision analytic models of HPV vaccination as they can determine whether vaccination is cost-effective or not. Accordingly, decision analytic models assessing cost-effectiveness of HPV vaccination in LMICs need to account for the distinct challenges that do not apply to high income countries to such an extent if the appropriate policy advice is to be given.
Therefore, we conducted a systematic review to assess how context-specific challenges in implementing and maintaining cervical cancer prevention and control strategies in LMICs were accounted for in cost-effectiveness analysis models of human papillomavirus (HPV) vaccination. The review specifically examines the following questions: (1) Does the existing HPV vaccination cost-effectiveness literature acknowledge the particular challenges of LMICs? (2) How were the LMIC-particular challenges accommodated in the models? (3) Is the uncertainty among the parameters that are particularly sensitive to the implementation challenges in LMICs so large that the policy recommendations are affected?
The key findings of the systematic review were that cost per vaccinated girl, vaccine coverage and screening coverage are highly uncertain parameters in model-based cost-effectiveness analysis (CEA) of human papillomavirus (HPV) vaccines in low and middle income countries. These uncertain parameters matter as they can reverse the conclusions regarding cost-effectiveness made by a CEA, thereby altering the resulting policy choice.
Our proposal for refining cost per vaccinated girl estimates for cost-effectiveness analysis model of HPV vaccination in LMICs involves adaptation of HPV vaccine delivery cost from other countries where vaccination has been implemented to the country of study. With regards to vaccination coverage rate, we believe that it will be most appropriate to use previous country-specific vaccine coverage performance as a base case assumption. Coverage rates of adolescent catch-up or booster vaccination programme could be used in countries or regions where such programme is in place, such as in the Middle East and North African region . However, in the absence of adolescent vaccination programme, coverage of Diphtheria-Tetanus-Pertusis (DTP3) could serve as a good proxy especially as vaccination coverage with the third dose of DTP vaccines among infants is the main indicator of immunization programmes’ performance and is used as a benchmark to qualify for Vaccine Alliance (Gavi) support . For screening coverage, we recommend the use of cervical cancer screening coverage rate of countries in the same geographical region for analysis assuming an organized national screening or increased future predicted screening. For instance, in the absence of local data African countries could employ the South African screening coverage rate about 20% as the base-case rather than assuming 70% coverage .
Written by Ekwunife OI, O’Mahony JF, Gerber Grote A, Mosch C, Paeck T, Lhachimi SK
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