develop CPGs, and for payers and policy makers.1 A brief overview of the current producers and users of SRs is provided at the end of the chapter. SRs can also inform medical coverage decisions and be used to set agendas and funding for primary research by highlighting gaps in evidence. Although the importance of SRs is gaining appreciation, the quality of published SRs is variable and often poor (Glasziou et al., 2008; Hopewell et al., 2008b; Liberati et al., 2009; Moher et al., 2007). In many cases, the reader cannot judge the quality of an SR because the methods are poorly documented (Glenton et al., 2006). If methods are described, they may be used inappropriately, such as in meta-analyses (Glenny et al., 2005; Laopaiboon, 2003). One cannot assume that SRs, even when published in well-regarded journals, use recommended methods to minimize bias (Bassler et al., 2007; Colliver et al., 2008; Roundtree et al., 2008; Song et al., 2009; Steinberg and Luce, 2005; Turner et al., 2008). Many SRs fail to assess the quality of the included research (Delaney et al., 2007; Mallen et al., 2006; Tricco et al., 2008) and neglect to report funding sources (Lundh et al., 2009; Roundtree et al., 2008). A plethora of conflicting approaches to evidence hierarchies and grading schemes for bodies of evidence is a further source of confusion (Glasziou et al., 2004; Lohr, 2004; Schünemann et al., 2003).

In its 2008 report, Knowing What Works in Health Care: A Roadmap for the Nation, the Institute of Medicine (IOM) recommended that methodological standards be developed for SRs that focus on research on the effectiveness of healthcare interventions and for CPGs (IOM, 2008). The report concluded that decision makers would be helped significantly by development of standards for both SRs and CPGs, especially with respect to transparency, minimizing bias and conflict of interest, and clarity of reporting. The IOM report was soon followed by a congressional mandate in the Medicare Improvements for Patients and Providers Act of 20082 for two follow-up IOM studies: one, to develop standards for conducting SRs, and the other to develop standards for CPGs. The legislation directs the IOM to recommend methodological standards to ensure that SRs and CPGs “are objective, scientifically valid, and consistent.”

In response to this congressional directive, the IOM entered into a contract with the Agency for Healthcare Research and Quality (AHRQ) in July 2009 to produce both studies at the same time.


The IOM Committee on Standards for Developing Trustworthy Clinical Practice Guidelines defines CPGs as “statements that include recommendations intended to optimize patient care that are informed by an SR of evidence and an assessment of the benefits and harms of alternative care options.”


Public Law 110-275, Section 304.

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