TY - JOUR
T1 - Synthesizing study results in a systematic review
AU - Verbeek, Jos
AU - Ruotsalainen, Jani
AU - Hoving, Jan L.
PY - 2012
Y1 - 2012
N2 - A single study rarely suffices to underpin treatment or policy decisions. This creates a strong imperative for systematic reviews. Authors of reviews need a method to synthesize the results of several studies, regardless of whether or which statistical method is used. In this article, we provide arguments for combining studies in a review. To combine studies, authors should judge the similarity of studies. This judgement should be based on the working mechanism of the intervention or exposure. It should also be assessed if this mechanism is similar for various populations and follow-up times. The same judgement applies to the control interventions. Similar studies can be combined in either a meta-analysis or narrative synthesis. Other methods such as vote counting, levels of evidence synthesis, or best evidence synthesis are better avoided because they may produce biased results. We support our arguments by re-analysing a systematic review. In its original form, the review showed strong evidence of no effect, but our re-analysis concluded there was evidence of an effect. We provide a flow-chart to guide authors through the synthesis and assessment process
AB - A single study rarely suffices to underpin treatment or policy decisions. This creates a strong imperative for systematic reviews. Authors of reviews need a method to synthesize the results of several studies, regardless of whether or which statistical method is used. In this article, we provide arguments for combining studies in a review. To combine studies, authors should judge the similarity of studies. This judgement should be based on the working mechanism of the intervention or exposure. It should also be assessed if this mechanism is similar for various populations and follow-up times. The same judgement applies to the control interventions. Similar studies can be combined in either a meta-analysis or narrative synthesis. Other methods such as vote counting, levels of evidence synthesis, or best evidence synthesis are better avoided because they may produce biased results. We support our arguments by re-analysing a systematic review. In its original form, the review showed strong evidence of no effect, but our re-analysis concluded there was evidence of an effect. We provide a flow-chart to guide authors through the synthesis and assessment process
U2 - https://doi.org/10.5271/sjweh.3201
DO - https://doi.org/10.5271/sjweh.3201
M3 - Review article
C2 - 22015561
SN - 0355-3140
VL - 38
SP - 282
EP - 290
JO - Scandinavian journal of work, environment & health
JF - Scandinavian journal of work, environment & health
IS - 3
ER -