Randomisation and masking
PTSD, DSM-5, Clinician-Administered PTSD
Eligible participants were randomly assigned (3:3:1) to iCT-PTSD, iStress-PTSD, or waiting list plus usual care, stratified by location (Thames Valley, London, or Sussex), duration of PTSD (<18 months or ≥18 months), and severity of PTSD symptoms on the PTSD Checklist for DSM-5 ([PCL-5]; high [≥49] Independent assessors conducting Clinician-Administered PTSD Scale (CAPS-5) interviews were masked to study group assignment, and participants were reminded not to disclose the trial condition to which they were assigned. If participants accidentally mentioned information that unmasked the assessor, this information was cut from the recording, which was then re-rated by another rater. Therapists, trial administrators, and participants were not masked to treatment allocation due to the nature of the intervention. Statistical analyses were done masked to treatment, with the treatments coded as A and B.