Network meta-analysis for evidence synthesis: what is it and why is it posed to dominate cardiovascular decision making?

Clinical decision-making requires synthesis of an often complex evidence base. Novel tools have been developed building upon the historical approach of reviewing the literature focusing on a specific topic. Stemming from qualitative reviews, systematic reviews of randomized clinical trials, typically encompassing statistical pooling with pairwise meta-analysis, have been devised and are now considered one of the uppermost ladders in the hierarchy of clinical evidence. In the last decade, the exponential growth in randomized trials and the introduction of original computational methods have created the novel opportunity to compare indirectly competing treatments, as well as combining effect estimates stemming from head-to-head trials with those obtained by indirect comparisons. These methods include adjusted indirect comparison meta-analysis, network meta-analysis, and mixed treatment comparison. While still the focus of intense research and debate, they represent a powerful tool for evidence synthesis and comparative effectiveness in cardiovascular research, and thus are likely to become increasingly popular and impactful in shaping research agenda and clinical practice. This is clearly highlighted by a number of recent landmark network meta-analyses on smoking cessation therapies, coronary stents, and management of patent foramen ovale in patients with history of cryptogenic stroke.