What happens to value of information measures as the number of decision options increases?
OBJECTIVE
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.
Barton
Pelham
P
Health Economics Unit, University of Birmingham, Birmingham, UK. p.m.barton@bham.ac.uk
D000367:Age Factors; D001499:Bayes Theorem; D002755:Choice Behavior; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D055088:Early Detection of Cancer / Q000191:economics*; D006801:Humans; D033181:Information Dissemination; D008962:Models, Theoretical; D019057:Quality-Adjusted Life Years