As evidence is generated, systematic analysis is essential to translate it into clinically useful practice guidelines and other clinician decision-support tools. Many organizations and initiatives in the United States are performing such analyses for M/SU health care. However, there is often little coordination of those efforts. Moreover, although the practice of evidence-based care is widely endorsed, there is not yet a shared understanding in M/SU health care (as is also the case in general health care [Steinberg and Luce, 2005]) of what constitutes a finding that a given practice is evidence-based. Views differ about the acceptability of various forms of evidence, what level of evidence is necessary for a practice to be recommended or endorsed as evidence-based (Tanenbaum, 2003), and whether knowledge of evidence-based care for a population can be adapted to meet each individual’s unique needs (Tanenbaum, 2005).
This lack of consensus prompted a call from Congress in 1999 for AHRQ to identify and describe sound methods for rating the strength of scientific evidence. AHRQ found several acceptable systems that address the essential considerations of (1) the aggregate quality ratings for individual studies; (2) the quantity of studies (number of studies, magnitude of observed effects, and sample size or power); and (3) consistency, or the extent to which similar and different study designs yield similar findings (West et al., 2002). However, AHRQ’s findings while helpful, do not resolve debates about whether a given intervention is evidence-based. Most evidence reviewers acknowledge that many interventions have varying degrees of evidence in their favor, ultimately necessitating a judgment as to whether the evidence supports recommending their use.
This judgment can often differ according to the entity conducting the evidence review but may be more susceptible to variation in M/SU than in general health care for several reasons. First, a greater number of organizations are involved in making determinations with regard to evidence-based practices in M/SU health care. As Chapter 7 attests, a greater number of professions (e.g., physicians, psychologists, counselors, marriage and family therapists) with their diverse traditions and training are involved in independently diagnosing and treating M/SU conditions than is the case for general health care. Their professional organizations are increasingly conducting evidence reviews and promulgating their own practice guidelines. Moreover, because M/SU problems and illnesses are addressed not only by the health care system, but also by the welfare, justice, and education systems, organizations and disciplines involved in these latter systems also are dedicating resources to evaluating the evidence and identifying evidence-based M/SU health care practices (see the Department of Justice’s What Works initiative in Table