Outcome Assessment by Central Adjudicators Versus Site Investigators in Stroke Trials: A Systematic Review and Meta-Analysis

Peter J. Godolphin, Philip M. Bath, Ale Algra, Eivind Berge, Martin M. Brown, John Chalmers, Lelia Duley, Misha Eliasziw, John Gregson, Jacoba P. Greving, Graeme J. Hankey, Naohisa Hosomi, S. Claiborne Johnston, Emily Patsko, Annamarei Ranta, Per Morten Sandset, Joaquín Serena, Christian Weimar, Alan A. Montgomery, Adjudicating Outcomes in Stroke Trials Collaboration

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Background and Purpose-In randomized stroke trials, central adjudication of a trial's primary outcome is regularly implemented. However, recent evidence questions the importance of central adjudication in randomized trials. The aim of this review was to compare outcomes assessed by central adjudicators with outcomes assessed by site investigators. Methods-We included randomized stroke trials where the primary outcome had undergone an assessment by site investigators and central adjudicators. We searched MEDLINE, EMBASE, CENTRAL (Cochrane Central Register of Controlled Trials), Web of Science, PsycINFO, and Google Scholar for eligible studies. We extracted information about the adjudication process as well as the treatment effect for the primary outcome, assessed both by central adjudicators and by site investigators. We calculated the ratio of these treatment effects so that a ratio of these treatment effects >1 indicated that central adjudication resulted in a more beneficial treatment effect than assessment by the site investigator. A random-effects meta-analysis model was fitted to estimate a pooled effect. Results-Fifteen trials, comprising 69 560 participants, were included. The primary outcomes included were stroke (8/15, 53%), a composite event including stroke (6/15, 40%) and functional outcome after stroke measured on the modified Rankin Scale (1/15, 7%). The majority of site investigators were blind to treatment allocation (9/15, 60%). On average, there was no difference in treatment effect estimates based on data from central adjudicators and site investigators (pooled ratio of these treatment effects=1.02; 95% CI, [0.95-1.09]). Conclusions-We found no evidence that central adjudication of the primary outcome in stroke trials had any impact on trial conclusions. This suggests that potential advantages of central adjudication may not outweigh cost and time disadvantages in stroke studies if the primary purpose of adjudication is to ensure validity of trial findings.

Original languageEnglish
Pages (from-to)2187-2196
Number of pages10
Issue number8
Publication statusPublished - Aug 2019
Externally publishedYes

Bibliographical note

© 2019 The Authors. Stroke is published on behalf of the American Heart Association, Inc., by Wolters Kluwer Health, Inc. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial License, which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited and is not used for commercial purposes.


  • adjudication
  • clinical trial
  • meta-analysis
  • stroke
  • systematic review


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