Study design
death, PTSD, DSM-5, traumatic
EVENT
This was a two-arm, parallel-group, single-blind, randomised controlled trial with a comparator arm receiving delayed access to active treatment (crossover). The analyses presented here followed an optimisation phase that used Bayesian adaptive design and sequential analyses, which are presented elsewhere [Inclusion criteria: Adults aged ≥18 years or older; worked in a clinical role in a National Health Service (NHS) ICU or equivalent during the COVID-19 pandemic; experienced at least 1 work-related traumatic event meeting DSM-5 criterion A for PTSD (“exposure to actual or threatened death, serious injury, or sexual violence” by “directly experiencing the traumatic event(s)” or “witnessing, in person, the event(s) as it occurred to others”); had intrusive memories of the event(s) and experienced ≥3 intrusive memories in the week before screening; had internet access; willing and able to be contacted by the research team during the study; willing and able to provide informed consent and attempt study procedures; and could speak, read and write English. Exclusion criterion was having fewer than three intrusive memories in the baseline week. Receipt of treatments for PTSD symptoms was not an exclusion criterion.Participants were recruited via email and social media advertisements sent to the ICS membership network as described [