In addition, staff conducted informal, structured interviews with other key stakeholders.

The committee recommends four standards for the assessment and qualitative and quantitative synthesis of an SR’s body of evidence. Each standard consists of two parts: first, a brief statement describing the related SR step and, second, one or more elements of performance that are fundamental to carrying out the step. Box 4-1 lists all of the chapter’s recommended standards. This chapter provides the background and rationale for the recommended standards and elements of performance, first outlining the key considerations in assessing a body of evidence, and followed by sections on the fundamental components of qualitative and quantitative synthesis. The order of the chapter’s standards and the presentation of the discussion do not necessarily indicate the sequence in which the various steps should be conducted. Although an SR synthesis should always include a qualitative component, the feasibility of a quantitative synthesis (meta-analysis) depends on the available data. If a metaanalysis is conducted, its interpretation should be included in the qualitative synthesis. Moreover, the overall assessment of the body of evidence cannot be done until the syntheses are complete.

In the context of CER, SRs are produced to help consumers, clinicians, developers of clinical practice guidelines, purchasers, and policy makers to make informed healthcare decisions (Federal Coordinating Council for Comparative Effectiveness Research, 2009; IOM, 2009). Thus, the assessment and synthesis of a body of evidence in the SR should be approached with the decision makers in mind. An SR using rigorous and transparent methods allows decision makers to discern what is known and not known about an intervention’s effectiveness and how the evidence applies to particular population groups and clinical situations (Helfand, 2005). Making evidence-based decisions—such as when a guideline developer recommends what should and should not be done in specific clinical circumstances—is a distinct and separate process from the SR and is outside the scope of this report. It is the focus of a companion IOM study on developing standards for trustworthy clinical practice guidelines.1

A NOTE ON TERMINOLOGY

The SR field lacks an agreed-on lexicon for some of its most fundamental terms and concepts, including what actually constitutes

1

The IOM report, Clinical Practice Guidelines We Can Trust, is available at the National Academies Press website: http://www.nap.edu/.



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