Gaps in completeness of reporting and methodological quality: a metaresearch study of 139 network meta-analyses published in January 2023 using PRISMA-NMA and AMSTAR-2

OBJECTIVES: Network meta-analysis (NMA) is a method for comparing multiple interventions simultaneously, combining evidence to estimate and rank their relative effectiveness and safety across a network of studies. This study evaluates (i) epidemiological and descriptive characteristics, (ii) reporting completeness, and (iii) methodological quality of NMAs.

STUDY DESIGN AND SETTING: In this metaresearch study (protocol at https://osf.io/pa6dz/), we searched PubMed for systematic reviews with NMAs indexed in January 2023. We extracted epidemiological and descriptive data, assessed reporting completeness using the modified Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for NMA, and evaluated the methodological quality using A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR-2).

RESULTS: Among the 139 NMAs, 77% were published in specialty journals (median journal impact factor [JIF] 4), and 52% originated from China. Reporting completeness and methodological quality were generally of a medium quality, with the median NMAs fulfilling 71% of the modified Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Network Meta-Analyses (PRISMA-NMA) and 63% of the AMSTAR-2 criteria. Items such as "network geometry" for modified PRISMA-NMA (15%) and "list of excluded studies" for AMSTAR-2 (12%) were frequently unfulfilled. Better reporting and methodological quality were associated with registered protocol, non-Chinese country, higher JIF, and larger author teams.

CONCLUSION: We highlight gaps in both reporting and methodological quality in NMAs. We recommend future authors to plan and conduct NMAs within a large author team that includes statistical experts and to strictly adhere to reporting and methodological quality standards. More attention should be given to the reporting of network geometry and documenting the list of excluded studies.