Some problems in applying evidence in clinical practice.

There is a considerable gap between sound evidence concerning health care interventions and the services that patients actually receive as health care. Practitioners and the health care system must overcome a number of barriers to narrow the gap. Viewed simplistically, there are three steps from evidence to practice: getting the evidence straight; developing clinical practice guidelines that are faithful to both the evidence and the clinical and personal situations of patients; and applying these guidelines to the right patient at the right time in the right way. Special problems in getting the evidence straight stem from difficulties in finding sound evidence. Lack of agreement on evidence standards undermine the effectiveness of authoritative practice guidelines. Applying evidence and practice guidelines effectively and efficiently is often thwarted by mismatches between evidence and usual practice circumstances. Time pressures undermine interpretation and application of evidence at every step. Understanding these problems may permit development of more effective strategies to bridge the gap between evidence and practice.