Navigating time and uncertainty in health technology appraisal: would a map help?

Healthcare systems are increasingly under pressure to provide funding for innovative technologies. These technologies tend to be characterized by their potential to make valued contributions to patient health in areas of relative unmet need, and have high acquisition costs and uncertainty within the evidence base on their actual impact on health. Decision makers are increasingly interested in linking reimbursement strategies to the degree of uncertainty in the evidence base and, as a result, reimbursement for innovative technologies is frequently linked to some form of patient access or risk-sharing scheme. As the dominant methods of economic evaluation report final outcomes only at the time horizon of the analysis, they present only aggregated information. This omits much of the information available on how net benefit is distributed within the time horizon. In this article, we introduce the Net Benefit Probability Map (NBPM), which maps net health benefit versus time to identify how certain decision makers can be about the benefit of technologies at multiple time points. Using an illustrative example, we show how the NBPM can inform decision makers about how long it will take for innovative technologies to 'pay off', how methodological choices on discount rates affect results and how alternative payment mechanisms can reduce the risk for decision makers facing innovative technologies.