What happens to value of information measures as the number of decision options increases?
通过一个假设癌症筛查模型，研究了当决策选项（如筛查年龄）数量增加时，完美信息期望值（EVPI）和成本效果可接受前沿（CEAF）的变化，发现CEAF高度依赖选项选择，而EVPI可通过有限选项集合理近似。
AIM: To explore what happens to the expected value of perfect information (EVPI) as an increasingly large number of decision options is considered. METHODS: A stylised model of screening for a hypothetical cancer. The model was used to test different possible ages for 'once in a lifetime' screening under a variety of assumptions about model parameter uncertainty. Initial model runs only considered screening at ages which are multiples of 16 years, then multiples of 8 years were allowed, then 4 years, etc. RESULTS: Effects of more refined choice sets on the cost-effectiveness acceptability frontier (CEAF) and EVPI are shown. The CEAF collapses to zero for threshold incremental cost-effectiveness ratios at which screening at some age is preferred to no screening, while the EVPI stabilises at a non-zero figure. CONCLUSIONS: The CEAF is likely to be highly dependent on the choice of options when these are a selection from a very large set of possible options. In contrast, the EVPI can be reasonably approximated by a model with a slightly limited choice set.