Some observations on attempts to measure appropriateness of care.

There are a growing number of published studies that suggest that much health care is delivered inappropriately. There are calls for measures of appropriateness to be used by purchasers and others to regulate or influence the delivery of health care. This paper explores assumptions inherent in results generated by a leading measure of appropriateness and concludes that there are considerable uncertainties about the measure's meaning, the magnitude of bias that it contains, and the degree to which its application can be generalised. Some of these uncertainties could be resolved if the tacit assumptions inherent in the generation of the criteria could be made explicit. Existing measures of appropriateness are not yet sufficiently robust to be used with confidence to influence or control the delivery of health care. They may have a use as an aid rather than as a constraint in clinical decision making. A randomised controlled trial could resolve whether patients achieve better outcomes if their care is influenced by appropriateness criteria.