General practice pp 1383, 1389

Randomised trials of health care interventions are increasingly attempting to tackle issues of cost effectiveness as well as clinical effectiveness. A good example of this appears in the two papers describing the clinical1 and economic evaluation2 of psychological therapies in primary care in this issue of the BMJ (pp 1383,1389). The use of clinical trials as a vehicle for prospective cost effectiveness analysis presents challenges for successful evaluation, and the methods of conducting trial based economic evaluation are still in their infancy.

Several commentators have emphasised that health economists should be involved from the outset in the design of trials that seek to report on cost effectiveness,3 rather than being asked to add in the economic variables as an adjunct to the main trial (in a so called “piggyback” arrangement).4 The reason for this is because design considerations are different for clinical and economic analyses.

The tendency of resource use variables to follow a skewed distribution5 means …