8-day Intensive Treatment Programme for PTSD and CPTSD in Sweden

1. Study aims and research questions The purpose of the study is to compare the outcomes and potential risks between two treatment methods for treatment-resistant PTSD and C-PTSD: 8-day intensive treatment and conventional treatment. Additionally, the study aims to investigate whether there are individual factors that influence the outcomes of each treatment format. Specific research questions:

• Can a difference in the severity of PTSD and C-PTSD be observed after 8-day intensive treatment? Does the outcome differ compared to conventional treatment for PTSD and C-PTSD?
• Are there individual factors that influence the treatment outcome? Does the impact of these factors differ between the study groups?
• Does participation in 8-day intensive treatment pose an increased risk of adverse, harmful effects or an increase in suicidal intentions during and after the treatment?

1. Method

2.1 Participants

Participants consist of individuals referred to the Adult Psychiatric Outpatient Clinic for Psychosis and PTSD at Södra Älvsborgs Hospital between August 2021 and December 2023. Inclusion criteria for participation: diagnosis of C-PTSD or PTSD with previous treatment attempts that have not been effective. Exclusion criteria: insufficient knowledge of the Swedish language to respond to questionnaires, need for an interpreter during treatment, use of benzodiazepines, acute suicidality, or dissociative identity disorder. All individuals who meet the inclusion criteria during the recruitment period are asked about their willingness to participate.

We calculated differences between two independent groups with means. The calculation was based on the PCL-5 and the results from the study by Wortmann et al. (2016). The power calculation was performed using G*Power 3.1.9.4 (Faul et al., 2007) With a power of 0.80, a significance level of 0.05, a two-sided test, Group 1 had a difference of 10 (SD 15), and Group 2 had a difference of 2 (SD 13). The effect size was 0.56, which corresponds to a moderate effect. This results in a total sample of 100, i.e., 50 participants in each group.

2.2 Procedure

Allocation to each intervention group follows the principles of person-centered care, where participants are considered competent to be involved in their treatment choice. Participants are provided with written and verbal information about the treatment options and given the opportunity to ask questions in order to make an informed decision.

2.3 Data collection

Data is collected in the two following ways:

1. Through questionnaires and clinician ratings conducted during the inclusion assessment and follow-up after treatment, the following data is collected:

• Trauma history (LEC-5),
• Diagnosis of PTSD or C-PTSD (ITI 3.2),
• Self-assessment of dissociative symptoms (DES II),
• Clinician rating of suicidal intentions (SSI).

1. Data is collected via the REDcap database before, during, and after treatment completion. Participants receive a printed QR code for each assessment point and complete the assessments via mobile phone or computer. If needed, assessments can be done manually. The digital assessments include:

• Background information such as demographic data, sick leave status, employment, psychiatric treatment history, and ongoing treatment.
• Self-report questionnaires measuring PTSD symptoms (PCL-5), C-PTSD symptoms (ITQ), and transdiagnostic screening of psychiatric symptoms (DSM-5 CCM Level 1).

2.4. Data analysis

Analysis of group differences and exploratory analyses will be conducted using statistical software (SPSS for Windows). Differences in background data and baseline data between groups will be tested using the Chi-square (X²) test for categorical data and independent t-tests for numerical data, or alternatively, the Mann-Whitney U test if the criteria for parametric statistics are not met for numerical data.

• Data from all included participants completing basline assessment will be used, regardless of the number of completed assessments. Data that are possible statistical outliers will be included in the analysis if they are not outside the expected clinical range for the specific measure. Intent-to-treat (ITT) analysis will be applied to analyze outcomes related to repeated measurements (PCL-5 and ITQ). For this purpose, Linear Mixed Model (LMM) will be used, allowing for the inclusion of all available data from participants across all time points.
• Difference between groups will be analyzed for means and standard deviations. Results will be presented with levels of signifiance (p.05) and effectsize, including confidence intervals.
• Exploratory analysis of moderating individual factors (baseline symptom measurement, demographics, comorbidity, trauma history) that may influence treatment outcomes will be conducted using multiple regression analysis.

1. Expected outcomes and contributions fot the field of knowledge

The study is expected to provide increased knowledge on whether 8-day intensive treatment has an impact on symptoms in treatment-resistant forms of PTSD and C-PTSD, and whether its effectiveness differs from traditional treatment. The study is also anticipated to enhance understanding of whether individual factors play a role in the choice of treatment.

Overall, the study aims to provide important insights into intensive treatment for C-PTSD and treatment-resistant PTSD in a Swedish context. This knowledge is expected to contribute to decisions on whether intensive treatment should be implemented in Swedish psychiatry.