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Original research
Agreement between core laboratory and study investigators for imaging scores in a thrombectomy trial
  1. Robert Fahed1,
  2. Malek Ben Maacha2,
  3. Célina Ducroux1,
  4. Naim Khoury3,
  5. Raphaël Blanc1,
  6. Michel Piotin1,
  7. Bertrand Lapergue4
  8. for the ASTER Trial Investigators
    1. 1 Interventional Neuroradiology Unit, Fondation Rothschild Hospital, Paris, France
    2. 2 Research and Biostatistics Unit, Fondation Rothschild Hospital, Paris, France
    3. 3 HSHS Neuroscience Center, HSHS St John’s Hospital, Springfield, Illinois, USA
    4. 4 Neurovascular Unit, Foch Hospital, Suresnes, France
    1. Correspondence to Dr Robert Fahed, InterventionalNeuroradiology Unit, Paris 75019, France; robert.fahed{at}


    Purpose We aimed to assess the agreement between study investigators and the core laboratory (core lab) of a thrombectomy trial for imaging scores.

    Methods The Alberta Stroke Program Early CT Score (ASPECTS), the European Collaborative Acute Stroke Study (ECASS) hemorrhagic transformation (HT) classification, and the Thrombolysis In Cerebral Infarction (TICI) scores as recorded by study investigators were compared with the core lab scores in order to assess interrater agreement, using Cohen’s unweighted and weighted kappa statistics.

    Results There were frequent discrepancies between study sites and core lab for all the scores. Agreement for ASPECTS and ECASS HT classification was less than substantial, with disagreement occurring in more than one-third of cases. Agreement was higher on MRI-based scores than on CT, and was improved after dichotomization on both CT and MRI. Agreement for TICI scores was moderate (with disagreement occurring in more than 25% of patients), and went above the substantial level (less than 10% disagreement) after dichotomization (TICI 0/1/2a vs 2b/3).

    Conclusion Discrepancies between scores assessed by the imaging core lab and those reported by study sites occurred in a significant proportion of patients. Disagreement in the assessment of ASPECTS and day 1 HT scores was more frequent on CT than on MRI. The agreement for the dichotomized TICI score (the trial’s primary outcome) was substantial, with less than 10% of disagreement between study sites and core lab.

    Trial registration number NCT02523261, Post-results.

    • stroke
    • MRI
    • CT
    • angiography

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    • Contributors RF: figures, study design, data collection, data analysis, statistical analyses, writing manuscript. MBM: data collection, data analysis, writing manuscript. CD: figures, data collection, data analysis, writing manuscript. NK: data analysis, writing manuscript. RB: data analysis, writing manuscript. MP: data analysis, writing manuscript. BL: study design, data collection, data analysis, writing manuscript.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Patient consent Not required.

    • Ethics approval Fondation Rothschild Ethics Committee.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement Data, analytic methods, and study materials will be made available to any researcher for the purposes of reproducing the results or replicating the procedure. Requests to receive these materials should be sent to the corresponding author, who will maintain their availability.

    • Collaborators ASTER Trial Investigators: Hocine Redjem, Gabriele Ciccio, Stanislas Smajda, Mikael Mazighi, Jean Philippe Desilles, Georges Rodesch, Arturo Consoli, Oguzhan Coskun, Federico Di Maria, Frédéric Bourdain, Jean Pierre Decroix, Adrien Wang, Maya Tchikviladze, Serge Evrard, Francis Turjman, Benjamin Gory, Paul Emile Labeyrie, Roberto Riva, Charbel Mounayer, Suzanna Saleme, Vincent Costalat, Alain Bonafe, Omer Eker, Grégory Gascou, Cyril Dargazanli, Serge Bracard, Romain Tonnelet, Anne Laure Derelle, René Anxionnat, Hubert Desal, Romain Bourcier, Benjamin Daumas-Duport, Jérome Berge, Xavier Barreau, Gauthier Marnat, Lynda Djemmane, Julien Labreuche, Alain Duhamel.