Large scale healthcare interventions are likely to improve the health of the public if the evidence clearly shows that the benefits outweigh harms and costs. Often, however, the evidence is not compelling, and well intended interventions may fail to improve health, or may even cause harm, while costing dearly. Moreover, when a large scale intervention is implemented without compelling evidence, wishful thinking may replace careful evaluation, and an unproved innovation may become an enduring but possibly harmful standard of care. Such interventions should be implemented, therefore, only when the evidence shows that expected benefits outweigh harms and costs and only when the effects of implementation will be evaluated systematically.1

Large scale healthcare interventions aim to influence clinical evaluation, treatment, or care of a large group of people. Some interventions are coercive, …