Estimating the cost effectiveness of screening tests.

A number of criteria have been postulated that a screening test should fulfill in order for it to be a good or worthwhile screening tool. However, it is a rare test which fulfills all the criteria that have been thought to be important. Therefore, there always exists some form of trade-off between, for example, the detection rate and the false-positive rate and cost. It is the magnitude and form of these trade-offs, which differ for each screening test, that are important, not whether a test fulfills some arbitrary set of criteria. In this paper, we describe some of the trade-offs which occur when appraising a screening test and we argue that listing arbitrary criteria is an unhelpful activity.