The attractiveness of network meta-analysis: a comprehensive systematic and narrative review

Network meta-analysis provides a global estimate of comparative treatment effectiveness combining both direct and indirect evidence. In the past decade, the medical literature has witnessed a rapid increase in the possibility to combine evidence from different treatment comparisons. This opportunity is attractive for clinicians since their major concern is to identify the single best available treatment. In addition, despite the sudden increase of publications concerning network meta-analysis, only a limited number focus on methodological and statistical aspects, and many issues remain unclear. The aim of our work was to explore and emphasize the potential attractiveness of network meta-analyses. We performed a systematic and narrative review (last updated on April 15, 2014) in order to assess the scholarly diffusion of network meta-analyses. The following data were collected: author identification, year and journal of publication, PubMed index, number of treatments and studies included, characteristics of network configuration, nature of primary outcome, clinical indication, type of intervention investigated and medical area. Since 2003 there has been an exponential increase in the number of published network meta-analyses. Out of 340 articles included according to our selection criteria, encompassing 248 treatment networks, cardiovascular and pulmonary diseases were the most prevalent topics, with an average of 5 treatments being compared stemming from an average of 10 controlled trials. In conclusion, network meta-analyses are becoming increasingly attractive as they offer a comprehensive framework for decision-making. Whether they will also contribute to improvements in patient outlook remains to be proven.