Group schema therapy for cluster-C personality disorders: A multicentre open pilot study.

BACKGROUND: Group schema therapy (GST) is increasingly popular as a treatment for personality disorders (PDs), including Cluster-C PDs. Individual ST has proven to be effective for Cluster-C PD patients, while the evidence for GST is limited. This study aimed to investigate the effectiveness of GST for Cluster-C PD. Moreover, differences between the specific Cluster-C PDs (avoidant PD, dependent PD and obsessive-compulsive PD) were explored. METHODS: A multicentre open trial was conducted, including 137 patients with a Cluster-C PD (avoidant PD: n = 107, dependent PD: n = 11 and obsessive-compulsive PD: n = 19). Patients received 30 weekly GST sessions with a maximum of 180 min of individual ST and five optional monthly booster sessions. Outcome measures including Cluster-C PD severity, general psychopathological symptoms, quality of life, functional impairment, happiness, PD-related beliefs, self-esteem, self-ideal discrepancy, schemas and schema modes were assessed at baseline until 2-year follow-up with semi-structured interviews and self-report measures. Change over time and differences between the specific Cluster-C PDs were analysed with mixed regression analyses. RESULTS: The outcome measures showed significant improvements for all Cluster-C PDs, with medium to large effect sizes after 2 years. A treatment dropout rate of 11.7% was found. There were some indications for differences between the Cluster-C PDs in severity at baseline, change trajectories and effectiveness of GST. CONCLUSIONS: This study demonstrated that GST is a promising treatment for Cluster-C PDs. The following step is a randomized controlled trial to further document the (cost-)effectiveness of GST.

Design of an RCT on cost-effectiveness of group schema therapy versus individual schema therapy for patients with Cluster-C personality disorder: the QUEST-CLC study protocol.

BACKGROUND: Given the high prevalence of Cluster-C Personality Disorders (PDs) in clinical populations, disease burden, high societal costs and poor prognosis of comorbid disorders, a major gain in health care can be achieved if Cluster-C PDs are adequately treated. The only controlled cost-effectiveness study published so far found Individual Schema Therapy (IST) to be superior to Treatment as Usual (TAU). Group ST (GST) might improve cost-effectiveness as larger numbers can be treated in (>50%) less time compared to IST. However, to date there is no RCT supporting its (cost-) effectiveness. The overall aim of this study is to assess the evidence for GST for Cluster-C PDs and to improve treatment allocation for individual patients. Three main questions are addressed: 1) Is GST for Cluster-C PDs (cost-)effective compared to TAU? 2) Is GST for Cluster-C PDs (cost-) effective compared to IST? 3) Which patient-characteristics predict better response to GST, IST, or TAU? METHODS: In a multicenter RCT, the treatment conditions GST, IST, and TAU are compared in 378 Cluster-C PD patients within 10 sites. GST and IST follow treatment protocols and are completed within 1 year. TAU is the optimal alternative treatment available at the site according to regular procedures. Severity of the Cluster-C PD is the primary outcome, assessed with clinical interviews by independent raters blind for treatment. Functioning and wellbeing are important secondary outcomes. Assessments take place at week 0 (baseline), 17 (mid-GST), 34 (post-GST), 51 (post-booster sessions of GST), and 2 years (FU). Patient characteristics predicting better response to a specific treatment are studied, e.g., childhood trauma, autistic features, and introversion. A tool supporting patients and clinicians in matching treatment to patient will be developed. An economic evaluation investigates the cost-effectiveness and cost-utility from a societal perspective. A process evaluation by qualitative methods explores experiences of participants, loved ones and therapists regarding recovery, quality of life, and improving treatment. DISCUSSION: This study will determine the (cost-)effectiveness of treatments for Cluster-C PDs regarding treatment type as well as optimal matching of patient to treatment and deliver insight into which aspects help Cluster-C-PD patients recover and create a fulfilling life. TRIAL REGISTRATION: Dutch Trial Register: NL9209 . Registered on 28-01-2021.