The economic perspective.

The rationale for the economic perspective on screening is presented and the particular relevance of economic evaluation highlighted. The principles of economic evaluation are described in terms of measuring and valuing the costs and outcomes associated with screening. The different types of economic evaluation are described with discussion of data sources. The problematic issues associated with time preferences and discounting and with the measurement and valuation of outcomes other than true positives are discussed. Issues associated with antenatal screening, in particular the inclusion of averted costs due to the termination of an affected pregnancy and the inclusion and valuation of the unborn child's utility, are also raised.