new, many current conventional medical practices did not follow what is now considered to be the normative pathway of translation because they became accepted practice before this pathway was fully established. Many practices that are widely accepted, however, continue to undergo scrutiny, and their indications often change as research identifies those patients who benefit the most from them. An example is coronary bypass surgery which became accepted treatment before undergoing controlled clinical trials. The evident effectiveness of coronary bypass surgery in reducing symptoms of stable angina fostered great enthusiasm for the procedure, with many clinicians assuming that its effectiveness would be similar in reducing the risks of heart attack and death because of coronary disease. When bypass surgery was already well established, a number of RCTs showed that it improved the life expectancies of patients with severe coronary artery disease but had little effect on patients with mild disease. In addition, it had no effect on heart attack rates. Similarly, patients with acute coronary syndromes that threatened to evolve into myocardial infarction received percutaneous coronary interventions long before RCTs showed that this strategy was superior (by a small margin) to thrombolysis with drugs.
In this idea pathway, the acceptance of new interventions in clinical practice depends on a cycle (Figure 7-1) that begins with a creative idea derived from either an advance in science or a clinical observation. That creative insight is the basis for hypotheses about treatment effectiveness. Hypotheses are tested through a series of evaluation steps before they are accepted, first by early adopters and then more widely. As acceptance grows, a number of forces shape the level of integration of the intervention into clinical practice. These forces may include difficulty in acquiring technical skills, the supply of practitioners or the capacity to deliver the intervention, and coverage decisions made by health plans and other payers. Patient demand for services also affects acceptance and integration. Patient demand is influenced by evidence of effectiveness, but it is also influenced