Critical reviews of economic analyses in order to make health care decisions for cancer.

The idea of promoting evidence based medicine, understood as practicing according to the best evidence based on exhaustive and systematic reviews of all available data, is very convincing and difficult to contest rationally. This certainly does not mean that the exact type of evidence to take into consideration is indisputable. Thus, Maynard [2] recently accused leading spokesmen for the evidence based medicine 'movement' of completely ignoring treatment costs by recommending that treatment decisions be made merely on the basis of efficacy data [3]. Concerning the establishment of the best current clinical evidence, many years of research and discussion have gradually developed into a 'science of systematic reviews', with at least broad agreement about the principles to follow when collecting, evaluating and summarizing evidence. With respect to establishing evidence on efficiency, i.e., the relation between clinical outcomes and the associated costs of treatment, the question about systematic reviews of evidence from primary studies is only just beginning to arise [4-10]. This article deals with some of the issues involved in systematic reviews of economic evaluations in health care. It is argued that the principal concern should be with the problems involved in carrying out secondary analyses, ie transferring the results of studies to other health care settings than the one in which the primary evaluation has been performed.