Abstract
The time when medicine could afford the luxury of a leisurely pace in identifying optimal practices at a reasonable cost has passed. Payers, providers, health care organizations, and more recently patients are clamoring for ways to deliver maximally effective care for the fewest dollars. How to identify the practices that represent such care is among the most pressing problems facing American medicine.An exclusive reliance on randomized controlled trials to provide definite information about effectiveness is not the answer. We cannot afford to conduct randomized controlled trials for every test, procedure, or medication in use. To do so would require . . .