The effect of animated consent material on participants' willingness to enrol in a placebo-controlled surgical trial: a protocol for a randomised feasibility study.

Background: Placebo-controlled surgical trials are recognised as the gold standard way to test the efficacy of a surgical procedure. Despite a rise in arthroscopic subacromial decompression (ASD) surgeries for the treatment of shoulder pain, only two placebo-controlled surgical trials have been conducted. These trials encountered significant recruitment challenges, threatening the external validity of findings. Difficulties with recruitment are common in clinical trials and likely to be amplified in placebo-controlled surgical trials. This mixed method feasibility trial aims to address the following questions: (i) Feasibility: What proportion of patients who have consented to undergo ASD report that they would be willing to enrol in a placebo-controlled trial for this procedure? (ii) Optimisation: Can patients' willingness to enrol in, or understanding of, such a trial be improved by supplementing written consent materials with a brief visual animation that outlines the details of the trial? And (iii) exploration: What factors influence patients stated willingness to enrol in such a trial, and how do they believe the recruitment process could be improved?

Methods: This study aims to recruit 80 patients on the waiting list for ASD. Participants will be randomised (1:1) to either view a brief video animation explaining the hypothetical placebo-controlled trial in addition to written information or to written information only. Participants in both groups will be required to state if they would be willing to opt-in to the hypothetical ASD trial after immediately being presented with the consent material and again 1 week after completion of the consent process. Patients in both groups will also be required to complete a measure of trial literacy. Twenty participants will be purposively sampled to take part in an embedded qualitative study exploring understanding of trial concepts and factors contributing to willingness to opt-in.

Discussion: This feasibility study will provide evidence for optimising participant recruitment into a placebo-controlled trial of ASD by consenting patients using animated trial information in addition to written information. This pilot and feasibility data may also be relevant to placebo-controlled surgical trials more broadly, which are characterised by recruitment challenges.

Trial Registration: ANZCTR, ACTRN12620001132932 , date October 30, 2020.