Bayesian value-of-infomation analysis - An application to a policy model of Alzheimer's disease

A framework is presented that distinguishes the conceptually separate decis ions of which treatment strategy is optimal from the question of whether mo re information is required to inform this choice in the future. The authors argue that the choice of treatment strategy should be based on expected ut ility, and the only Valid reason to characterize the uncertainty surroundin g outcomes of interest is to establish the value of acquiring additional in formation. A Bayesian decision theoretic approach is demonstrated through a probabilistic analysis of a published policy model of Alzheimer's disease. The expected value of perfect information is estimated for the decision to adopt a new pharmaceutical for the population of patients with Alzheimer's disease in the United States. This provides an upper bound on the value of additional research. The value of information is also estimated for each o f:the model inputs. This analysis can focus future research by identifying those parameters where more precise estimates would be most valuable and in dicating whether an experimental design would be required. We also discuss how this type of analysis can also be used to design experimental research efficiently (identifying optimal sample size and optimal sample allocation) based on the marginal cost and marginal benefit of sample information. Val ue-of-information analysis can provide a measure of the expected payoff fro m proposed research, which can be used to set priorities in research and de velopment. It can also inform an efficient regulatory framework for new hea lthcare technologies: an analysis of the value of information would define when a claim for a new technology should be deemed substantiated and when e vidence should be considered competent and reliable when it is not cost-eff ective to gather any more information.