The Impact of Alternative Specifications of Uncertainty Relating to Extrapolation in Decision Models

Abstract

Economic evaluations that incorporate value-of-information analysis frequently conclude that the greatest information value relates to replicating short-term clinical trials. This study builds on recent guidance relating to extrapolation in economic evaluation by assessing the impact of alternative approaches to representing the uncertainty around unobserved/extrapolated data with respect to incremental outcomes and value of information. When the uncertainty over unobserved and observed data is considered distinct but correlated (i.e., has a joint distribution), it is demonstrated that the value to replicating short-term clinical studies is lessened and that further studies relating to the unobserved periods likely provide more value.