Economic evaluation of hepatitis B vaccination in low-income countries: using cost-effectiveness affordability curves

Objective We sought to describe a method that explicitly considers both a health-care programme's cost-effectiveness and its affordability. For illustration, we apply the method to the programme to vaccinate infants against hepatitis B in the Gambia. Methods We synthesized selected data and developed a computer-based model from the societal and payer perspectives to evaluate the cost-effectiveness of routine infant vaccination against hepatitis B in the Gambia compared with no vaccination. The primary outcome measure was cost per averted disability-adjusted life year (DALY), which was expressed in 2002 US dollars. We used Monte Carlo methods for uncertainty analysis to examine the affordability of the programme from the payer's perspective, and we derived an affordability curve and cost-effectiveness affordability curves for the programme. Findings In the Gambia, vaccinating infants against hepatitis B is highly cost-effective. Compared with offering no intervention, the vaccination programme would cost US$ 28 per DALY averted from the societal perspective or US$ 47 per DALY averted from the payer's perspective. The programme also has the potential to be affordable, starting at a relatively low budget of US$ 160 000 per year. Combining the two dimensions of the outcome measure, the probability that vaccinating infants would be both cost-effective and affordable is 40% at an annual programme budget of US$ 182 000 (the estimated total programme cost from the payer's perspective), given a threshold cost-effectiveness value of US$ 47 per DALY averted. Conclusion In the face of uncertainties about both the health and economic consequences of a vaccine programme, as well as the availability and magnitude of resources needed to fund the programme, cost-effectiveness affordability curves can provide information to decision-makers about the probability that a programme will be both cost-effective and affordable: these are distinct but equally relevant considerations in resource-poor settings.