dations) and tools (e.g., computerized physician order entry systems) are created to aid clinical care decisions each year. As stated in Chapter 1, clinical practice guideline (CPG) development has evolved dramatically in the 20 years since the Institute of Medicine (IOM) first became involved in this area. This chapter provides a brief review of modern applications of scientific evidence in the development of clinical care and evolution of CPGs. It then offers an overview of many participants in current CPG development and use, providing selected examples.

Before the end of the 20th century, clinical decisions were based largely on experience and skill (the “art” of medicine); medical teaching and practice were dominated by knowledge delivered by medical leaders (Davidoff, 1999; Eddy, 2005; Evidence-Based Medicine Working Group et al., 1992). Although some form of evidence has long contributed to clinical practice, there was no generally accepted, formal way of ensuring a scientific, critical approach to clinical decision making (Daly, 2005). The 1992 Evidence-Based Medicine Working Group, primarily McMaster University professors, who created a training program to teach EBM to internal medicine residents, described the historical paradigm of medical decision in the following sentences:

• “Unsystematic observations from clinical experience are a valid way of building and maintaining one’s knowledge about patient prognosis, the value of diagnostic tests, and the efficacy of treatment.

• The study and understanding of basic mechanisms of disease and pathophysiologic principles are a sufficient guide for clinical practice.

• A combination of thorough traditional medical training and common sense is sufficient to allow one to evaluate new tests and treatments.

• Content expertise and clinical experience are a sufficient base from which to generate valid guidelines for clinical practice.” (Evidence-Based Medicine Working Group et al., 1992, p. 2421)

The modern commitment to EBM dates to the 1970s, when a growing body of health services research refuted long-held assump-