Abstract P6-12-10: Method development for a ‘Study within a Trial’ using a cluster stepped wedge trial design: Evaluating a patient decision aid video on patients’ decisional conflict in the PRIMETIME study
Authors: Bhattacharya Indrani Subarna , Haviland Joanne S , Balasopoulou Ada , Stones Liba , Stobart Hilary , Turner Lesley , Hopwood Penelope , Bliss Judith M , Coles Charlotte E 
Published: March 2020

Abstract
Background: PRIMETIME is a UK-led prospective biomarker directed cohort study aiming to identify a group of breast cancer patients who can safely avoid radiotherapy following breast conserving surgery. This group is deemed to be at such a low risk of local relapse that the potential benefits of radiotherapy are unlikely to outweigh the risks. The uncertainty patients face regarding healthcare decisions is known as ‘decisional conflict’ which may increase when a component of standard of care is removed. Patient decision aids (PDA) are interventions which help patients to weigh up the risks and benefits of treatments. Evidence suggests PDA reduce decisional conflict. The study within a trial (SWAT) concept enables trialists to conduct research embedded within a larger trial in an economic and efficient manner. A SWAT testing whether the introduction of a PDA video reduces decisional conflict was conducted within the PRIMETIME study. The method development of the PRIMETIME SWAT is described.
Methods: The SWAT was embedded within PRIMETIME after PRIMETIME had opened to recruitment. All eligible patients approached for the PRIMETIME study were eligible for the PRIMETIME SWAT. The SWAT utilised a cluster stepped-wedge trial design. Each cluster consisted of the radiotherapy centre and any peripheral centres referring into that radiotherapy centre. At the outset of the SWAT, all sites utilised the standard written information when discussing the trial with patients as had been envisaged in the original protocol. At pre-specified time-points each cluster “crossed over” to additionally incorporate the PDA video in the information provided to patients eligible for PRIMETIME. Decisional conflict was assessed in clusters prior to and following implementation of the PDA. The PDA was designed in collaboration with PRIMETIME patient advocates to be used in addition to the standard written information, explaining the same risks and benefits of radiotherapy but using an enhanced video format. Access to the PDA was restricted for healthcare professionals as well as patients until the cluster had crossed over to the intervention group to ensure that healthcare professionals did not alter the way in which they presented the study having watched the video. The primary endpoint was reduction in decisional conflict as measured on the decisional conflict scale.
Discussion: The eligible population for the SWAT was greater than the population of the main PRIMETIME study (i.e. including patients who declined PRIMETIME), to try and obtain a SWAT sample representative of the general population. The cluster aspect of the stepped-wedge design ensured all patients in a cluster would receive uniform information which would simplify processes for sites and avoid cross-contamination between patients. The stepped-wedge aspect enabled all clusters to have access to the PDA by the end of the trial. The PDA was designed to complement the standard written information and explain the risks and benefits of radiotherapy in a different format using a video. If PDA are found to reduce decisional conflict within treatment de-escalation trials, this will provide the evidence to increase resources into the development of PDAs in future trials.
Citation Format: Indrani Subarna Bhattacharya, Joanne S Haviland, Ada Balasopoulou, Liba Stones, Hilary Stobart, Lesley Turner, Penelope Hopwood, Judith M Bliss, Charlotte E Coles. Method development for a ‘Study within a Trial’ using a cluster stepped wedge trial design: Evaluating a patient decision aid video on patients’ decisional conflict in the PRIMETIME study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-12-10.