The evolution of the randomized controlled trial and its role in evidence-based decision making.

The randomized controlled trial has been used in medical research for a little over half a century. This manuscript provides an overview of some of the history and evolution of the randomized controlled trial during this period. There exists hierarchies of evidence for therapeutic, diagnostic and prognostic questions, and the randomized controlled trial is at the top of the therapeutic hierarchy. Despite being at the top of the therapeutic hierarchy randomization in itself does not guarantee the trial results approximate the true effect. Issues that result in systematic and nonsystematic deviations from the truth in randomized controlled trials must also be considered. We present a model for evidence-based decision making that includes the following components: the clinical state, patient preferences, research evidence from a range of studies and clinical expertise. We discuss the role of the randomized controlled trial within evidence-based decision making.