2.2 Background on systematic reviews A systematic literature review uses specific explicit, thorough methods to identify, select and critically appraise relevant research studies on a well- defined topic. The basic elements of a systematic review are:
an extensive, systematic search of research literature for relevant
systematic evaluation of the quality of relevant studies
systematic synthesis of the findings in the best quality studies
Systematic reviews aid decision-makers by sifting through an enormous literature to find the best quality studies and then synthesize them. Decision-makers usually do not have the time, resources and/or expertise to undertake these tasks themselves.
Systematic reviews are more highly regarded than traditional literature reviews because they employ such rigorous, transparent methods. This means they are less vulnerable to the biases of a single researcher.
As with previous systematic reviews on primary prevention at IWH (Cole et al., 2004; Tompa et al., 2004) this review is a particular type of systematic review known as “best-evidence synthesis” (Slavin, 1995). This approach advocates using explicit, thorough methods to select the best studies from the literature which address a particular research question.
The Slavin (1995) approach includes generating a detailed presentation of individual study characteristics, along with either a qualitative or quantitative synthesis of results2. This allows readers of the systematic review to actually judge the quality of individual studies. Slavin also encourages reviewers to critique and interpret the body of extracted literature in the manner of a narrative review.
2.3 Challenges in conducting a systematic review on OHSMSs There were several challenges in carrying out this review:
There is no consensus on the definition of an OHSMS. Yet a working definition was needed to support decisions about which studies would be included in the review and which would be excluded.
The literature in which evidence on OHSMS effectiveness is found is diverse. Diversity increases the time and resources required during
2 Systematic reviews can sometimes yield a quantitative summary of the effect of an intervention, based on the pooling of the results from the review’s studies, as in a meta- analysis. This requires there to be several studies of a similar nature. If this condition is not met, then a qualitative summary of the studies is appropriate.
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