Background: Network meta-analysis is a study design that allows indirect comparisons between interventions when there are no studies with direct comparisons. Although there is no standard method, crucial points, as the level of similarity within studies (called transitivity or similarity) and, the analysis and results (called consistency or coherence) became well known. Considering the recent growth and the lack of well-established standards for network meta-analysis, a question arises: What are the characteristics of network meta-analysis reviews from Cochrane?
Objectives: To describe the characteristics of network meta-analysis reviews published by Cochrane.
Methods: We performed a descriptive study at the Brazilian Cochrane Centre (BCC). We included Cochrane Systematic Reviews using the expression 'network meta-analysis' in any part of the text. We selected the studies after full readings. The extracted outcomes were: review characteristics, related review group, year and stage of publication.
Results: The search was conducted in March 2015. We identified 104 studies and excluded 71 studies after full text reading. From the 33 remaining studies, 16 were reviews, 12 protocols and 5 overviews distributed in 21 review groups; 48% of studies were published in 2014 (16/23); 36% mentioned 'network meta-analysis' in the title. Considering only finished studies (reviews and overviews), 57% (12/21) mentioned having performed transitivity assessment and 57% mentioned that that assessed inconsistency, although they were not exclusively the same studies. Graphs and figures representing the network meta-analysis were found in only three reviews. Eight reviews mentioned the use of STATA and seven mentioned WinBUGS as the software for analysis.
Conclusions: We believe that there is a need to define description standards for networks meta-analysis within Cochrane, with emphasis on transitivity and inconsistency. Standardizing graphs and figures would also be beneficial. Those were present in a minority of studies.