Inpatient Dialectical Behaviour Therapy combined with trauma-focused therapy (DBT-PTSD) for PTSD and borderline personality disorder symptoms: Study design of the naturalistic Trauma Therapy Study (TTS)
Authors: Kamstra Annemieke C. , De Vries Sybolt O. , Brilman Maarten , Vasilev Petty , Alma Manna A. , Asselt Antoinette D. I. Van , De Wolf Mia , Schoevers² Robert A. , Jörg² Frederike 
Published: November 2024

Background
Childhood traumatization can result in physical and mental health problems in adulthood, such as post-traumatic stress disorder (PTSD), which negatively influences quality of life and social functioning. Similarly, personality disorder may be a consequence from childhood traumatization, and these conditions often co-occur. Although evidence based trauma treatments may benefit patients with PTSD after childhood abuse and comorbid personality disorders, they are less effective than in patients who were traumatized in adulthood, and drop-out is also substantial. The current study aims to assess the effects of inpatient dialectical behaviour therapy combined with prolonged exposure (DBT-PTSD) on severity of PTSD, dissociation, parasuicidal behaviour and borderline personality disorder (BPD) symptomatology in patients with severe PTSD and any type of comorbid psychiatric disorders. Secondary outcomes are social functioning, quality of life, borderline and cluster C personality disorder symptoms as treatment predictors, treatment trajectories, patients’ experiences and health economic consequences.
Methods
The naturalistic Trauma Therapy Study (TTS) with a longitudinal, within-subjects design is conducted from January 2019 until May 2025 in a specialised mental healthcare provider in the Netherlands. Patients with severe PTSD and comorbid conditions who are referred to inpatient DBT-PTSD are included into the study after signing informed consent. Based on power analyses a total sample size of N = 56 is needed. Measurements take place before the waiting list period, at pre- and posttreatment and at six- and twelve-months follow-up. Patients fill in a daily DBT-PTSD diary, which will give insight into individual symptom trajectories. Statistical analyses include two-sided paired samples t-tests, linear mixed model analyses and cost-effectiveness analyses. Qualitative interviews are conducted within two years posttreatment and analysed using a phenomenological approach. We will correct for chance capitalisation by using a conservative α-level of .01. Multiple imputation will be used to handle missing data.
Discussion
Research on the effects of integrated treatment programs for patients with severe PTSD and co-morbid conditions is scarce. This study will extend the current knowledge on the effects of inpatient DBT-PTSD on PTSD and BPD symptoms and patients’ social functioning and quality of life. In addition, it provides insight into individual symptom trajectories and experiences, inspiring future treatment improvements for patients with severe psychopathology.
Trial registration
The local Medical Ethical Committee approved the study (NL669060018, RTPO1044/ 01.10.2018), which was preregistered at the Dutch registration database Centrale Commissie Mensgebonden Onderzoek and the International Clinical Trials Registry Platform (NL-OMON46167/ 01.10.2018).