Bibliographic study showed improving statistical methodology of network meta-analyses published between 1999 and 2015.

OBJECTIVE To assess the characteristics and core statistical methodology specific to network meta-analyses (NMAs) in clinical research articles. STUDY DESIGN AND SETTING We searched Medline, Embase and the Cochrane Database of Systematic Reviews from inception until April 14, 2015 for NMAs of randomized controlled trials (RCTs) including at least four different interventions. Two reviewers independently screened potential studies, while data abstraction was performed by a single reviewer and verified by a second. RESULTS A total of 456 NMAs, which included a median (interquartile range) of 21 (13 to 40) studies and 7 (5 to 9) treatment nodes were assessed. A total of 125 NMAs (27%) were star networks; this proportion declined from 100% in 2005 to 19% in 2015 (p=0.01 by test of trend). An increasing number of NMAs discussed transitivity or inconsistency (0% in 2005, 86% in 2015, p<0.01) and 150 (45 %) and used appropriate methods to test for inconsistency (14% in 2006, 74% in 2015, p<0.01). Heterogeneity was explored in 256 NMAs (56%), with no change over time (p=0.10). All pairwise effects were reported in 234 NMAs (51%), with some increase over time (p=0.02). The hierarchy of treatments was presented in 195 NMAs (43%), the probability of being best was most commonly reported (137 NMAs, 70%) but use of SUCRA (surface under the cumulative ranking curves) increased steeply (0% in 2005, 33% in 2015, p