Dimensions of Evidence

In the J anuary-February issue of the JABFP, John Geyman introduced the subject of evidence-based medicine by presenting an overview of the gap between evidence and practice and the challenges ahead as we attempt to fill the gap.l Several parent concerns are driving the evidence-based approach. First, the usual sources of clinical advice, expert opinions, have proved variable and unreliable. 'When one asks a group of experts a straightforward clinical question, one is as likely as not to get a range of answers rather than a single answer based on evidence. The American Medical Association Diagnosis and Treatment Therapeutic Assessment (DATTA) program in which experts are polled always impresses by the dispersion of the responses as much as by the (uncommon) convergence of opinion. An evidencebased approach should be able to tell us which of the options is best supported by scientific data.