The evidence base for complementary and alternative medicine: methods of Evidence Mapping with application to CAM

There is widespread concern regarding the adequacy of evidence for specific practices under the rubric of "complementary and alternative medicine" (CAM).

To map the evidence pertaining to many commonly used CAM practices.

In 2000, the Yale Prevention Research Center was funded by the Centers for Disease Control and Prevention to conduct a "systematic review" of the evidence underlying CAM. The investigative team, working in collaboration with CAM practitioners, developed a systematic and replicable 9-step process termed evidence mapping. The process stipulates means for specifying the boundaries of the subject to be mapped in MeSH terms, and the characteristics used to situate retrieved articles in the overall map of evidence.

Yale Prevention Research Center, Derby, CT.

Steps completed thus far have led to the identification of over 4,000 papers distributed across 207 condition-treatment pairs. Of these pairs, 58% (n = 121) have been studied with one or more RCTs (1,070 total RCTs), and 23% (n = 47) have been the subject of one or more meta-analyses (86 total meta-analyses). Thirty-seven condition/treatment pairs (18%) had no identifiable supporting studies.

The novel methods of evidence mapping reported are useful and practical in characterizing the extent, distribution, and methodologic quality of research pertaining to a broad topic in medicine. Applied to CAM, they suggest that summary judgments about the quantity or quality of underlying evidence are overly simplistic.