Here's some food for thought on this question from the Yemen Observer. A snip:
Evidence based drug therapy (EBT) means integrating the best evidence, the individual characteristics of the patient, and individual clinical expertise, into a decision making process which leads to optimal drug therapy. A group of Yemeni and Gulf doctors say it is a complex process that requires a detailed understanding of the evidence, including how the evidence was derived and an appreciation of the magnitude of the benefits and/or risks.
The doctors published their study in the Yemen Health and Medical Research Journal. The study says that evidence-based medicine (EBM) is a style of practice in which doctors manage problems by reference to valid and relevant information. Unfortunately, research consistently has shown that clinical decisions rarely are based on the best available evidence.