Does prospective acceptability of an intervention influence refusal to participate in a randomised controlled trial? An interview study

Background: The generalizability of findings of Randomised Controlled Trials (RCTs) is undermined by low or biased recruitment. Reasons for participant refusal are infrequently reported in published literature. Aims: To apply the Theoretical Framework of Acceptability (TFA) to: (1) explore patient-reported reasons for declining to participate in a RCT comparing a new service model (patient-initiated appointments) with standard care (appointments scheduled by clinician) for managing blepharospasm and hemifacial spasm; (2) to explore associations between decliners' perceptions of acceptability and non-participation. Method: Eligible patients (n = 242) were approached to participate in the trial. Phase 1: decliners provided a brief reason for refusal. Reasons were analysed descriptively and reviewed against TFA constructs. Phase 2: Consecutive decliners participated in short semi-structured interviews, to explore their reasons for refusal in more depth. Interviews were transcribed and analysed, with the TFA as a coding framework. Results: Eighty-seven (36%) eligible patients refused trial participation; all provided a reason. From interviews with 15 decliners (17%), four key beliefs about acceptability were identified: happy with standard care (n = 41) (49%), anticipated burden of patient-initiated service, lack of confidence in ability to engage with new service and uncertainties about effectiveness of new service. Two themes reflected non-TFA factors: trial participation a low priority and burden of completing trial documentation. Conclusion: Reasons for refusal trial participation included: (a) reasons directly associated with intervention acceptability, and (b) reasons associated with trial participation more broadly. The TFA facilitated identification of problematic aspects of the new appointment booking system which could be addressed to enhance acceptability