Improvement needed in the network geometry and inconsistency of Cochrane network meta-analyses: a cross-sectional...

The aim of the study was to investigate the general characteristics and methodological and reporting quality of network meta-analyses (NMAs) published in the Cochrane library.

We conducted a comprehensive search of the Cochrane library in April 2018 and included 42 NMAs. We used the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) 2 to assess methodological quality and Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA)-NMA for reporting quality. Stratified analysis and correlation analysis were conducted to explore the factors that might affect the quality.

A total of 42 NMAs investigated 29 topics. The compliance of PRISMA-NMA was moderate. Only 26.2% NMAs described the geometry of network, 64.3% presented the network plot, and 33.3% fully assessed the inconsistency. The overall methodological quality was low. Only 11.9% NMAs explained the selection of study designs, and 40.5% investigated the publication bias. The compliance of PRISMA-NMA was higher with the increase of the AMSTAR 2 compliance rates (Spearman's ρ = 0.630, P = 0.000). NMAs with statistical or epidemiological authors often better reported the titles (P = 0.032). Compared with nonfunding NMAs, nonindustry funding NMAs often better reported data collection process (P = 0.028), planned methods of analysis (P = 0.034), and synthesis of results (P = 0.028).

The quality still needs to be further improved, especially referring to the assessment of publication bias, the geometry of network, and assessment and exploration of inconsistency.