Introduction
death, anxiety, traumatic, post-traumatic stress disorder, PTSD, depression, deaths, trauma
DISORDER, EVENTS
Healthcare staff commonly experience and witness difficult events such as sudden or tragic deaths as part of their daily work which are potentially psychologically traumatic [Intensive care unit (ICU) staff represent a discrete group for whom the adverse impact of the pandemic has been well established. In the UK intensive care units expanded beyond capacity, workforce to patient ratios had to be reduced, staff were unable to deliver the same level of attention to care, and in the first wave there were higher mortality rates and, therefore higher rates of witnessing death, and a lack of family visiting the ICU. Midway through the first wave of the pandemic in 2020, approximately two-fifths of staff working in ICUs in England reported symptoms consistent with a probable mental health disorder including post-traumatic stress disorder (PTSD), anxiety and depression [To ameliorate the widespread negative impact of the pandemic on the mental health of frontline healthcare staff, effective interventions are urgently needed that can be disseminated quickly and at scale [Existing evidence-based interventions after psychological trauma are clearly highly important [We proposed a brief, mechanistically-informed behavioural intervention approach [We have tested the intervention previously using an experimental medicine approach in a series of controlled laboratory experiments of analogue trauma with non-clinical volunteers, and showed a reduction in the number of intrusive memories in the first week post-intervention after watching a trauma film [This clinical trial advanced on previous trials by testing (a) treatment of established, existing intrusive memories i.e., delivered after a few days to many years post trauma (rather than only as prevention with delivery in the early aftermath of trauma cf. Iyadurai et al., 2018 [We developed a digital version of the imagery-competing task intervention, to facilitate remote delivery under pandemic conditions and for future scalability. All components were integrated on a secure web platform accessed via smartphone, tablet or computer. The intervention package included step-by-step written guidance, instructional video animations, embedded ratings and integrated methods for recording and tracking the number of intrusive memories to guide intervention use. The intervention was delivered in a first session guided by trained researchers, with subsequent sessions self-administered but with optional researcher support.This paper is complementary to our sequential Bayesian analysis aimed at optimising the imagery-competing intervention and increasing trial efficiency [