Quest for optimal treatment of cluster-C personality disorders: evaluating schema therapy formats in a multicentre randomised controlled trial
14 affiliations
- 1Department of Clinical Psychology, University of Amsterdam, Amsterdam, The Netherlands
- 2Department of Psychological Methods, University of Amsterdam, Amsterdam, The Netherlands
- 3Department of Health Services Research, Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, The Netherlands
- 4Trimbos Institute, Utrecht, The Netherlands
- 5PsyQ Utrecht, Utrecht, The Netherlands
- 6PsyQ Zaandam, Zaandam, The Netherlands
- 7PsyQ Amsterdam, Amsterdam, The Netherlands
- 8PsyQ Rotterdam, Rotterdam, The Netherlands
- 9Academic Centre for Trauma and Personality, Amsterdam, The Netherlands
- 10IPGGZ Groningen, Groningen, The Netherlands
- 11IPGGZ Veendam, Veendam, The Netherlands
- 12Emergis, Goes, The Netherlands
- 13Department of Medical and Clinical Psychology, Tilburg University, Tilburg, The Netherlands
- 14Department of Personality Disorders, GGZ Oost Brabant, Helmond, The Netherlands
Abstract
Background: Schema therapy (ST) is proven to be effective for cluster-C personality disorders (PDs). Recently, a group format of ST (GST) has gained popularity but has not been compared with other treatments.
Objective: To compare the effectiveness of GST to individual ST (IST) and specialised treatment as usual (sTAU) for cluster-C PDs.
Method: We conducted a multicentre parallel-group, randomised controlled trial (QUalitative and Effectiveness Study to select optimal Treatment for Cluster-C PD) comparing 1 year of GST and IST with open-ended sTAU, with a follow-up assessment 2 years after start of treatment. Outpatients (>18 years) with a primary cluster-C PD were recruited and assigned to GST (30 weekly sessions plus 4 monthly booster sessions), IST (50 sessions with decreasing frequency) or sTAU (routine care in PD-specialised departments). The primary outcome was cluster-C PD severity change.
Results: 369 participants (mean (SD) age, 37.24 (11.21) years; 242 (65.6) female) received GST (46.6%), IST (26.0%) or sTAU (27.4%). At 1 year, GST was superior to sTAU (d=0.33, 95% CI 0.05 to 0.61, p=0.02), and IST was superior to sTAU (d=0.41, 95% CI 0.10 to 0.72, p=0.010). GST and IST did not differ significantly (d=0.08, 95% CI −0.19 to 0.35, p=0.57). No significant differences were found at 2 years (GST-sTAU: d=0.12, 95% CI −0.18 to 0.42, p=0.44; GST-IST: d=0.11, 95% CI −0.18 to 0.39, p=0.46; IST-sTAU: d=0.23, 95% CI −0.11 to 0.56, p=0.18). Treatment retention in IST (92.7%) was superior to sTAU (78.2%) but did not differ significantly with GST (84.9%) at 1 year. At 2 years, treatment retention in IST and GST remained the same and was both superior to sTAU (72.3%).
Conclusion: Both GST and IST outperformed sTAU after 1 year, although differences were no longer evident at follow-up. GST and IST showed higher retention rates than sTAU.
Clinical implications: These findings support GST and IST as good treatment options for cluster-C PDs.
Trial registration number: NL-OMON19942.
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BibTeX
@article{venhuizen2026quest,
title = {{Quest for optimal treatment of cluster-C personality disorders: evaluating schema therapy formats in a multicentre randomised controlled trial}},
author = {Anne-Sophie S M Venhuizen and Iuno Z Groot and Raoul P P P Grasman and Silvia M A A Evers and Joël R Van Aalderen and Mascha Nuijten and Elvan Tutkun and Susanne Dalmeijer and Kasper Nikkels and Myrte Maarschalkerweerd and Charlotte M E Van Ginkel and Agatha Ph Hollander and Fatima Jegić and Lotte Timmerman and Nathan Bachrach and Arnoud Arntz},
journal = {BMJ Mental Health},
year = {2026},
month = oct,
doi = {10.1136/bmjment-2026-302929},
url = {https://doi.org/10.1136/bmjment-2026-302929},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Quest for optimal treatment of cluster-C personality disorders: evaluating schema therapy formats in a multicentre randomised controlled trial
AU - Anne-Sophie S M Venhuizen
AU - Iuno Z Groot
AU - Raoul P P P Grasman
AU - Silvia M A A Evers
AU - Joël R Van Aalderen
AU - Mascha Nuijten
AU - Elvan Tutkun
AU - Susanne Dalmeijer
AU - Kasper Nikkels
AU - Myrte Maarschalkerweerd
AU - Charlotte M E Van Ginkel
AU - Agatha Ph Hollander
AU - Fatima Jegić
AU - Lotte Timmerman
AU - Nathan Bachrach
AU - Arnoud Arntz
PY - 2026
DA - 2026/10/26
JO - BMJ Mental Health
DO - 10.1136/bmjment-2026-302929
UR - https://doi.org/10.1136/bmjment-2026-302929
AB - Background: Schema therapy (ST) is proven to be effective for cluster-C personality disorders (PDs). Recently, a group format of ST (GST) has gained popularity but has not been compared with other treatments. Objective: To compare the effectiveness of GST to individual ST (IST) and specialised treatment as usual (sTAU) for cluster-C PDs. Method: We conducted a multicentre parallel-group, randomised controlled trial (QUalitative and Effectiveness Study to select optimal Treatment for Cluster-C PD) comparing 1 year of GST and IST with open-ended sTAU, with a follow-up assessment 2 years after start of treatment. Outpatients (>18 years) with a primary cluster-C PD were recruited and assigned to GST (30 weekly sessions plus 4 monthly booster sessions), IST (50 sessions with decreasing frequency) or sTAU (routine care in PD-specialised departments). The primary outcome was cluster-C PD severity change. Results: 369 participants (mean (SD) age, 37.24 (11.21) years; 242 (65.6) female) received GST (46.6%), IST (26.0%) or sTAU (27.4%). At 1 year, GST was superior to sTAU (d=0.33, 95% CI 0.05 to 0.61, p=0.02), and IST was superior to sTAU (d=0.41, 95% CI 0.10 to 0.72, p=0.010). GST and IST did not differ significantly (d=0.08, 95% CI −0.19 to 0.35, p=0.57). No significant differences were found at 2 years (GST-sTAU: d=0.12, 95% CI −0.18 to 0.42, p=0.44; GST-IST: d=0.11, 95% CI −0.18 to 0.39, p=0.46; IST-sTAU: d=0.23, 95% CI −0.11 to 0.56, p=0.18). Treatment retention in IST (92.7%) was superior to sTAU (78.2%) but did not differ significantly with GST (84.9%) at 1 year. At 2 years, treatment retention in IST and GST remained the same and was both superior to sTAU (72.3%). Conclusion: Both GST and IST outperformed sTAU after 1 year, although differences were no longer evident at follow-up. GST and IST showed higher retention rates than sTAU. Clinical implications: These findings support GST and IST as good treatment options for cluster-C PDs. Trial registration number: NL-OMON19942.
SN - 2755-9734
ER -