Undertaking network meta-analyses

This chapter provides an overview of the concepts, assumptions and methods that relate to network meta-analyses and to the indirect intervention comparisons on which they are built. It first describes what an indirect comparison is and how it can be made in a simple trio of interventions. The chapter then introduces the notion of transitivity (and its statistical analogue, coherence) as the core assumption underlying the validity of an indirect comparison. It also provides guidance on the design of a Cochrane Review with multiple interventions and the appropriate definition of the research question with respect to selecting studies, outcomes and interventions. The chapter further briefly describes the available statistical methods for synthesizing the data, estimating the relative ranking and assessing coherence in a network of interventions. Finally, it provides approaches for evaluating confidence in the evidence and presenting the evidence base and the results from a network meta-analysis.