Borrowing of strength from indirect evidence in 40 network meta-analyses

Abstract

Objective: Network meta-analysis (NMA) is increasingly being used to synthesize direct and indirect evidence and help decision makers simultaneously compare multiple treatments. We empirically evaluate the incremental gain in precision achieved by incorporating indirect evidence in NMAs. Study Design and Setting:We performed both network and pairwise meta-analyses on 40 published datasets of multiple-treatment comparisons. Their results were compared using the recently proposed borrowing of strength (BoS) statistic, which quantifies the percentage reduction in the uncertainty of the effect estimate when adding indirect evidence to an NMA. Results:We analyzed 915 possible treatment comparisons, from which 484 (53%) had no direct evidence (BoS = 100%). In 181 comparisons with only one study contributing direct evidence, NMAs resulted in reduced precision (BoS < 0) and no appreciable improvements in precision (0 < BoS < 30%) for 104 (57.5%) and 23 (12.7%) comparisons, respectively. In 250 comparisons with at least two studies contributing direct evidence, NMAs provided increased precision with BoS ≥ 30% for 166 (66.4%) comparisons. Conclusion:Although NMAs have the potential to provide more precise results than those only based on direct evidence, the incremental gain may reliably occur only when at least two head-tohead studies are available and treatments are well connected. Researchers should routinely report and compare the results from both network and pairwise meta-analyses.

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“…three or more) in CHR for psychosis trials using direct and indirect comparisons of interventions within and across RCTs based on a common comparator (such as needs-based interventions or placebo). Although NMAs have several advantages, one such advantage being the ability to compare interventions that have not been directly compared in an RCT, it is recommended that researchers report and compare the results from both pairwise and NMAs for a comprehensive understanding of the literature 75 .…”

A systematic review and network meta-analysis of injectable antibiotic options for the control of bovine respiratory disease in the first 45 days post arrival at the feedlot

“…It is often the case, however, that an insufficient number of trials are available for a pairwise meta-analysis. In such situations, network meta-analysis can be used to borrow information from the network of available evidence in order to obtain estimates of comparative efficacy (Taylor et al, 2010;Jackson et al, 2017;Lin et al, 2019). Several network meta-analyses have been conducted to evaluate the comparative efficacies of antibiotics for the treatment and control of BRD in beef production (O'Connor et al, 2013(O'Connor et al, , 2016Abell et al, 2017).…”

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“…, where RV refers to relative variance [11]. This ratio has also been described as the efficiency, "E" [10,23]. An equivalent but alternative method, decomposition of the score function for β, has advantage in that it defines appropriate study weights within an MVMA [11].…”

“…BoS may be conceptualised as a comparison of variances of the estimated r th component of β under the uni- and multivariate models , where RV refers to relative variance [ 11 ]. This ratio has also been described as the efficiency, “E” [ 10 , 23 ]. An equivalent but alternative method, decomposition of the score function for β, has advantage in that it defines appropriate study weights within an MVMA [ 11 ].…”