An epidemic of redundant meta‐analyses

Abstract

Background: Meta-analyses are widely used to strengthen available evidence and obtain more precise estimates of treatment effect than any individual trial. Paradoxically, multiplication of meta-analyses on the same topic can lead to confusion as practitioners no longer benefit from a rapid and synthetic response. This phenomenon may appear disproportionate when the number of published meta-analyses exceeds the number of original studies.Objectives: To describe an example of redundant meta-analyses published in the same area with the same randomized clinical trials (RCTs).Methods: A systematic review was performed to identify all published meta-analyses of original RCTs that compared direct oral anticoagulants with low molecular weight heparins in cancer patients with venous thromboembolism (VTE). Forest plots were used to represent the meta-analyses results for efficacy (VTE recurrence) and safety (major bleeding) endpoints. An authors' network was constructed to explore the links between the authors of the published meta-analyses.Results: In the past 3 years, four original RCTs were the subject of 20 published metaanalyses by 142 authors: five, four, and 11 meta-analyses pooled the data of two, three, and four RCTs, respectively. The results of meta-analyses were similar regarding the risks of VTE recurrence and major bleeding. The 11 meta-analyses of four RCTs were published within 6 months of the publication of the last RCT. Conclusions:The epidemic proportions of such redundant literature and authorship could be moderated by developing "living" meta-analyses and encouraging authors of new RCTs to update the corresponding meta-analysis in the same paper as their original research.

Chinese Medicine as an Adjunctive Treatment for Gastric Cancer: Methodological Investigation of meta-Analyses and Evidence Map

“…A systematic review with meta-analysis (MA) is widely recognized as the highest level of evidence in the EBM field ( Abushouk et al, 2021 ), but the reliability of pooled results reported in MAs is often hampered by methodological weaknesses ( Ioannidis, 2016 ). Furthermore, redundant and conflicting MAs on the same topic can confuse clinicians ( Chapelle et al, 2021 ), even leading to clinical decision-making errors and secondary harms to the relevant patients.…”

Kanglaite (Coix Seed Extract) as Adjunctive Therapy in Cancer: Evidence Mapping Overview Based on Systematic Reviews With Meta-Analyses

“…A systematic review with or without meta-analysis is often considered the highest level of evidence in the evidence-based field of healthcare (Brunström et al, 2022), and it usually serves as the cornerstone of evidence-based clinical practices (Lu et al, 2021b;Yao et al, 2021). Unfortunately, many existing systematic reviews with or without meta-analyses may be redundant, useless, confusing, or even misleading owing to overlapping or inadequate reporting, or serious methodological weaknesses (Shea et al, 2017;Chapelle et al, 2021;Hoffmann et al, 2021). Several systematic reviews with meta-analyses (Huang et al, 2020;Kong et al, 2021;Zhu et al, 2021) of KLT for cancers or conditions related to cancers have been published in recent years.…”

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“…Chapelle et al suggested that the multiplication of redundant meta-analyses raises scientific, ethical, and economic questions for researchers and publishers [ 25 ]. The scientific harm of redundant reviews can be seen as an accumulation of avoidable research waste.…”