This is a monocentric, controlled, prospective, randomised trial. (RCT). The study population is outpatients with psychotic illness and comorbid post-traumatic stress disorder who have applied for outpatient psychotherapy at the psychotherapeutic outpatient clinic (HSA) of the Medical School Hamburg. It will be investigated whether trauma therapy (Prolonged Exposure) reduces PTSD and psychosis symptoms in comparison to the waiting group. The study will be conducted from 01.09.2023 to 30.04.2028. Patients with suitable symptoms should be seen in the psychotherapeutic outpatient (psychotherapeutic consultation hours) at the HSA should be made aware of the study.
In the next step, a detailed diagnosis is made and, if consent is given and the inclusion criteria listed below are met, the patients are enrolled in the study.
The sample size for the longitudinal intent-to-treat (ITT) analysis with a linear mixed model (LMM) was chosen. Models (LMM) was calculated based on a previous RCT (Van den Berg et al., 2016, effect size for PE in CAPS versus waitlist (TAU) d = 0.78, p \< 0.001; effect size for PE in paranoia versus waitlist (TAU) d = 0.62, p = .005). ITT analyses with LLM are relatively robust to missing data, despite which we calculate a 20% dropout rate. With an alpha of 0.05; a mean effect size of 0.5, 3 measurement replicates (baseline measurement T0, post-treatment T1, 6-month follow-up after post, T2), we require 28 patients per treatment arm. A total of 56 patients will be included in the study.
