The primary objective with this study is to investigate the short-term efficacy (primary endpoint at week 3) of Internet-delivered cognitive behavior therapy (ICBT) provided soon after trauma. The secondary objective is to investigate the long-term efficacy (primary endpoint at week 7) of ICBT. 100 participants recently exposed to a potentially traumatic event will be randomised to either ICBT or assessment only.

PRIMARY OBJECTIVE

The primary objective with this study is to investigate the short-term efficacy (primary endpoint at week 3) of Internet-delivered cognitive behavior therapy (ICBT) provided soon after trauma.

SECONDARY OBJECTIVES The secondary objective is to investigate the long-term efficacy (primary endpoint at week 7) of ICBT.

Trial design: Randomized trial where participants are allocated to either ICBT (n=50) or control group (assessment only; n=50). Participants randomized to control group are subsequently offered identical ICBT treatment, so that all participants will eventually receive treatment.

All participants are assessed at baseline (W0), post-treatment (primary endpoint; W3) and at one-month follow-up (secondary endpoint; W7). Long-term follow-up assessments are also conducted at 6- and 12-months. The primary outcome measure is also measured weekly from baseline and up to the 1-month follow-up (W7).

Primary outcome measure used are the Posttraumatic Stress Disorder Checklist for Diagnostic and Statical Manual, Fifth Edition (PCL-5). Secondary outcome measures used are Montgomery Åsberg Depression Rating Scale - Self-report (MADRS-S), Euroqol (EQ-5D) and Trimbos and Institute of Medical Technology Assessment Cost Questionnaire for Psychiatry (TIC-P).

Participants are self-referred through advertisements in newspapers, web-pages, social media and at primary care, psychiatric and emergency clinics throughout Sweden. Interested applicants do an Internet-administered screening on an encrypted webpage using the PCL-5, MADRS-S, Alcohol User Disorders Identification Test (AUDIT), Drug User Disorders Identification Test (DUDIT), TIC-P, questions about inclusion and exclusion criteria and also give general background information. Written information about the study is given including objectives, benefits, risks and requirements imposed by the study.

An assessor calls the participant and conducts a structured clinical interview including The Mini-International Neuropsychiatric Interview (M.I.N.I.). The aim of this interview is to preliminary assess inclusion criteria and rule out exclusion criteria. Information is also given over the phone by the interviewer about the study protocol.

Safety parameters Participants will have the opportunity to report any adverse events during treatment, at posttreatment and follow-up assessment.

Data collection: Data will be collected electronically via the treatment platform.

Main statistical analysis: Between-group estimates on outcome are done using a mixed-effects regression model with repeated measurements. All analyses will be done according to intention to treat and post hoc per protocol analyses will also be conducted.

Inclusion Criteria:

• • Experienced psychological trauma in the past two months according to criterion A for PTSD in the DSM-5 (exposed to death, threatened death, actual or threatened serious injury, or actual or threatened sexual violence).

  • At least mild clinical symptoms assessed using the PCL-5
  • ≥ 18 years
  • Situated in Sweden
  • Informed consent

Exclusion Criteria:

• Other serious comorbidity as primary concern (ongoing substance dependence, untreated bipolar disorder, psychotic symptoms, severe depression, borderline personality disorder, high suicidal risk according to the M.I.N.I.)
• Not fluent speaking in Swedish
• Receiving CBT for trauma-related symptoms
• Ongoing trauma-related threat (e.g. living with a violent spouse)