• Danny A Young-Afat, Roxanne Gal, Sophie Gerlich, Johannes P M Burbach, Joanne M van der Velden, Desireé H J G van den Bongard, Martijn P W Intven, Nicolien Kasperts, Anne M May, Rieke van der Graaf, Carla H van Gils, and Helena M Verkooijen.
• Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands; Division of Imaging and Oncology, University Medical Center Utrecht, Utrecht, The Netherlands. Electronic address: d.a.youngafat@umcutrecht.nl.
• J Clin Epidemiol. 2021 Feb 1; 130: 135-142.

Background And ObjectiveThe Trials within Cohorts design aims to reduce recruitment difficulties and disappointment bias in pragmatic trials. On cohort enrollment, broad informed consent for randomization is asked, after which cohort participants can be randomized to interventions or serve as controls without further notification. We evaluated patients' recollection, understanding, and acceptance of broad consent in a clinical oncology setting.MethodsWe surveyed 610 patients with cancer participating in ongoing TwiCs; 482 patients (79%) responded, of which 312 patients shortly after cohort enrollment, 108 patients after randomization to an intervention (12-18 months after cohort enrollment), and a random sample of 62 cohort participants who had not been selected for interventions (1-6 months after cohort enrollment).ResultsShortly after providing cohort consent, 76% of patients (238/312) adequately remembered whether they had given broad consent for randomization. Of patients randomly offered interventions, 76% (82/108) remembered giving broad consent for randomization; 41% (44/108) understood they were randomly selected, 44% (48/108) were not interested in selection procedures, and 10% (11/108) did not understand selection was random. Among patients not selected for interventions, 42% (26/62) understood selection was random; 89% felt neutral regarding the scenario of "not being selected for an intervention while your data were being used in comparison with patients receiving interventions," 10% felt reassured (6/62) and 2% scared/insecure (2/62).ConclusionPatients adequately remember giving broad consent for randomization shortly after cohort enrollment and after being offered an intervention, but recollection is lower in those never selected for interventions. Patients are acceptant of serving as control without further notifications.Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.

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