ISRCTN16806208.

Study name	Public title: A randomised controlled trial of therapist‐assisted online psychological therapies for post‐traumatic stress disorder Scientific title: A randomised controlled trial of therapist‐assisted online psychological therapies for post‐traumatic stress disorder
Methods	Design: single‐blind, randomised controlled trial, with an embedded process study Location or setting: UK
Participants	Sample size: 217 participants (target) Inclusion criteria Aged 18 years and above Diagnosis of PTSD (as assessed with the Structured Clinical Interview for DSM‐5) Their current re‐experienced symptoms are linked to 1 or 2 discrete traumatic events that they experienced in adulthood or adolescence, or several traumatic episodes during a longer period of high threat (e.g. domestic abuse, war zone experiences). PTSD is the main psychological problem needing treatment. Willing and able to provide informed consent Able to read and write in English Access to internet Willing to be randomly allocated to one of the psychological treatments or wait If taking psychotropic medication, the dose must be stable for at least 1 month before randomisation. If currently receiving psychological therapy for PTSD, this treatment must have ended before randomisation. Exclusion criteria History of psychosis Current substance dependence Current borderline personality disorder Acute serious suicide risk Recruitment: completed
Interventions	Allocation using a 3:3:1 ratio Experimental 1: internet‐delivered cognitive therapy (iCT‐PTSD) Experimental 2: internet‐delivered stress‐management (iStress‐PTSD) Comparator: wait‐list
Outcomes	PTSD (PCL‐5, CAPS‐5, IES‐R) (timing of assessment: 6 weeks, 13 weeks, 26 weeks, 39 weeks, 65 weeks) Depression (PHQ‐9) (timing of assessment: 6 weeks, 13 weeks, 26 weeks, 39 weeks, 65 weeks) Anxiety (GAD‐7) (timing of assessment: 6 weeks, 13 weeks, 26 weeks, 39 weeks, 65 weeks) Disability (Work and Social Adjustment Scale) (timing of assessment: 6 weeks, 13 weeks, 26 weeks, 39 weeks, 65 weeks) Sleep problems (Insomnia Sleep Index) (timing of assessment: 6 weeks, 13 weeks, 26 weeks, 39 weeks, 65 weeks) Wellbeing (WHO Five Well‐being Index) (timing of assessment: 6 weeks, 13 weeks, 26 weeks, 39 weeks, 65 weeks) QoL (Endicott QoL Scale) (timing of assessment: 6 weeks, 13 weeks, 26 weeks, 39 weeks, 65 weeks) Health economics (timing of assessment: 6 weeks, 13 weeks, 26 weeks, 39 weeks, 65 weeks) Process measures (timing of assessment: 6 weeks, 13 weeks, 26 weeks, 39 weeks, 65 weeks) Therapeutic alliance (timing of assessment: 2 and 6 weeks) Satisfaction (timing of assessment: 13 weeks) Primary endpoint at 13 weeks
Starting date	Study start date: 15 December 2017 Study end date: 31 December 2021 (estimated)
Contact information	Name(s): Prof Anke Ehlers, University of Oxford E‐mail: anke.ehlers@psy.ox.ac.uk
Notes	Trial registry:ISRCTN Registry Trial registration number: ISRCTN16806208 Funding source: Wellcome Trust