Abstract
BACKGROUND: Personality disorders (PDs) are highly prevalent, impairing, and societally burdening conditions which can be treated effectively. Specialist psychotherapies are the first-choice treatment, but accessibility is hampered by implementation and sustainability issues. Manualised generalist treatments were designed as active control conditions to specialist psychotherapies in several effectiveness trials; their comparable performance led to them being regarded as more accessible alternatives to specialist psychotherapies. The Guideline-Informed Treatment for PDs (GIT-PD) is such a generalist treatment, which has shown promise and is broadly disseminated in the Netherlands and Belgium. However, there is an urgent need for controlled head-to-head comparisons of generalist and specialist treatments for PDs. Therefore, this study poses three main questions: 1) Is generalist treatment non-inferior compared to specialist treatment for severe PDs? 2) Is generalist treatment cost-effective compared to specialist treatment? 3) Which combination of patient characteristics predicts differential treatment outcomes between generalist and specialist treatments? METHODS: P-DAET is a pragmatic multicentre randomised controlled non-inferiority trial. In total, 358 adult treatment-seeking participants with severe PDs will be included in five Dutch mental healthcare institutions. Participants are equally randomised to manualised generalist (GIT-PD) or specialist treatment (Mentalisation-Based Treatment/Schema Therapy). The primary outcome is improvement in personality functioning, assessed through assessor-blinded clinical interviews and supplemented with self-report questionnaires. Symptom severity and psychosocial functioning are important secondary outcomes. Participants complete assessments at 7 time-points: baseline (T0), 3 (T1), 6 (T2), 12 (T3), 18 (T4), 24 (T5), and 30 months (T6) after the start of treatment. The primary endpoint is at 18 months. An economic evaluation will be executed alongside the RCT. Differential treatment response based on candidate predictors at the patient level will be explored using a personalised advantage index (PAI). DISCUSSION: P-DAET will determine the (cost-)effectiveness of generalist versus specialist treatment for severe PDs. This study will provide novel insights into the applicability of these treatments and their differential treatment response, enabling effective and personalised allocation of limited specialist treatment resources, while contributing to more accessible and good-enough care for individuals with severe PDs. TRIAL REGISTRATION: ClinicalTrials.gov: NCT06789380. Retrospectively registered on February 5, 2025.