Clinical Evidence will be updated periodically, and eventually will lead to a family of products available in electronic and print form.
Clinical practice guidelines can be defined as “systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances” (Institute of Medicine, 1992). Guidelines build on syntheses of the evidence, but go one step further to provide formal conclusions or recommendations about appropriate and necessary care for specific types of patients (Lohr et al., 1998). As a practical tool to influence practice, guidelines have been used in continuing medical education and clinical practice, as well as to make decisions about benefits coverage and medical necessity.
Guidelines have proliferated at a rapid pace during the last decade. During the early 1990s, the Agency for Health Care Policy and Research (now the Agency for Healthcare Research and Quality) sponsored an ambitious program for guideline development, which led to the specification of about 20 guidelines across a wide variety of clinical areas (Agency for Healthcare Research and Quality, 2000a; Perfetto and Stockwell Morris, 1996). The efforts in this area were eventually curtailed in favor of establishing the Evidence-Based Practice Centers in partnership with private-sector organizations (Lohr et al., 1998). Specialty societies, professional groups, health plans, medical centers, utilization review organizations, and others have also developed many practice guidelines.
Guidelines vary greatly in the degree to which they are derived from and consistent with the evidence base, for several reasons. First, as noted above, there is much variability in the quality of systematic reviews, which are the foundation for guidelines. Second, guideline development generally relies on expert panels to arrive at specific clinical conclusions. Judgment must be exercised in this process because the evidence base is sometimes weak or conflicting, or lacking in the specificity needed to develop recommendations useful for making decisions about individual patients in particular settings (Lohr et al., 1998).
In an effort to organize information on practice guidelines and to identify those having an adequate evidence base, the Agency for Healthcare Research and Quality, in partnership with the American Medical Association and the American Association of Health Plans, has developed a National Guideline Clearinghouse, which became fully operational in 1999 (Eisenberg, 2000a). The Clearinghouse provides online access to a large and growing repository of evidence-based practice guidelines.
Developing and disseminating practice guidelines alone has minimal effect on clinical practice (Cabana et al., 1999; Hayward, 1997; Lomas et al., 1989; Woolf, 1993). But a growing body of evidence indicates that guidelines implemented with patient-specific feedback and/or computer-generated reminders lead to significant improvements (Dowie, 1998; Grimshaw and Russell, 1993). More