Background: Unanticipated responses by research participants can influence randomised controlled trials (RCTs) in multiple ways, many of which are poorly understood. This study used qualitative interviews as part of an embedded process evaluation to explore the impact participants may have on the study, but also unintended impacts the study may have on them.
Aim: The aim of the study was to explore participants' experiences and the impact of trial involvement in a pilot RCT in order to inform the designing and delivery of a definitive RCT.
Methods: In-depth interviews with 20 participants (10 in the intervention and 10 in the control group) enrolled in a stroke rehabilitation pilot trial. A modified framework approach was used to analyse transcripts.
Results: Participation in the study was motivated partly by a desperation to receive further rehabilitation after discharge. Responses to allocation to the control group included an increased commitment to self-treatment, and negative psychological consequences were also described. Accounts of participants in both control and intervention groups challenge the presumption that they were neutral, or in equipoise, regarding group allocation prior to consenting to randomisation.
Conclusions: Considering and exploring participant and participation effects, particularly in the control group, highlights numerous issues in the interpretation of trial studies, as well as the in ethics of RCTs more generally. While suggestions for a definitive trial design are given, further research is required to investigate the significant implications these findings may have for trial design, monitoring and funding.
Trial registration: ClinicalTrials.gov, NCT02429180 . Registered on 29 April/2015.
Keywords: Equipoise; Qualitative; Randomisation; Rehabilitation; Stroke; Trial design.