There is high level of uncertainty surrounding the health and cost outcomes of vaccination programs, particularly in low- and middle-income countries. Few value of information (VOI) analyses have been applied to vaccination programs to help prioritize research in such settings. Our objective is to illustrate the potential role of VOI analysis for a new vaccine in a middle-income country setting, using as example a potential maternal group B streptococcal (GBS) vaccine program in South Africa.
Method:
We developed a probabilistic decision-analytic model to project the health (disability-adjusted life years [DALYs]) and economic (2010 US$) impact of a GBS vaccination program in South Africa, compared with the following strategies: doing nothing, risk factor-based intrapartum antibiotic prophylaxis (RFB-IAP), and RFB-IAP plus vaccination. We conducted Monte Carlo simulations and calculated the expected value of perfect information (EVPI), which indicates the maximum returns on future research, at the population level. We also calculated the expected value of partial perfect information (EVPPI), which indicates where further information on particular parameters would be most valuable, for the incidence of early- and late-onset GBS disease, the two most influential parameters identified in one-way sensitivity analysis.
Result:
For a 10-year time horizon, population EVPI was the highest, $26.6 million, at a willingness-to-pay of $1,760/DALY averted. For the same horizon, population EVPPI for the two incidence rates was highest, $3.2 million, at $1,740/DALY averted. At a willingness-to-pay of $7,272, South Africa’s 2010 per capita gross domestic product (based on the World Health Organization’s recommendations), the overall optimal strategy based on net benefit was RFB-IAP plus vaccination, and both population EVPI and EVPPI were zero, implying that more precise information would not change the decision that RFB-IAP plus vaccination is most cost-effective.
Conclusion:
The value of future research depends critically on willingness-to-pay for improved health. Our analysis suggests that further research to reduce uncertainty about a new GBS vaccine program may provide little value in South Africa, a middle-income country with a relatively high willingness-to-pay. However, for lower willingness-to-pay values that might apply in low-income countries, further research on GBS disease incidence could be worthwhile.
See more of: The 35th Annual Meeting of the Society for Medical Decision Making