NMA: Network meta-analysis based on multivariate meta-analysis and meta-regression models in R

Network meta-analysis has become an established methodology within systematic reviews for comparing the effectiveness of multiple treatments, and it has been now a standard approach in comparative effectiveness research. However, the underlying statistical methods are often highly technical for non-statisticians in practice, and no freely available software package has been developed that can handle a general framework based on the multivariate meta-analysis and meta-regression models. To address these issues, we developed NMA, a comprehensive and user-friendly R package that covers extensive analysis and graphical tools of network meta-analysis with simple commands. The NMA package provides generic functional tools for evidence synthesis based on the multivariate meta-analysis models, network meta-regression, assessment of heterogeneity and inconsistency, comparative effectiveness analyses, and a range of graphical tools. In addition, NMA includes data-handling functions that facilitate the integration of both arm-level data and summary statistics easily. In this article, we provide a gentle introduction to the NMA package and illustrate its application through a case study of a network meta-analysis of antihypertensive drugs.