Randomized Controlled Trial of the Effectiveness of the Combination of...


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Title Randomized Controlled Trial of the Effectiveness of the Combination of Cognitive Behavioral Therapy and Schema Therapy in Anxiety Disorders with a Comorbid Cluster C Personality Disorder
Period 06 / 2008 - unknown
Status Current
Research number OND1334440
Data Supplier ZonMw Projectenpoort


The objective of this project is to gain knowledge about the how and when of cognitive behavioral treatment (CBT) of Axis I anxiety disorders when there is co-morbidity of an Axis II cluster C personality disorder. It tries to answer the question whether a treatment of both Axis I and Axis II disorders is more effective than treatment of solely the Axis I or Axis II disorder.
Background: DSM-IV Cluster C personality disorders are the most prevalent personality disorders (Torgersen et al, 2001, Torgersen, 2005). This is also true for the Dutch general population (Sytema & Koopmans, 1998). The prevalence, according to the authors, ranges from 4.4 5.2 %. Research on the comorbidity of personality disorders and anxiety disorders suggests that a common personality pattern, with predominantly Cluster C personality disorders, is characteristic for all anxiety disorders (Van Velzen & Emmelkamp, 1999). In existing Dutch guidelines of the Werkgroep angststoornissen (2003) and the Werkgroep Persoonlijkheidsstoornissen (2007) it is stated that there is no research available for the treatment of the co-occurrence of Axis I and Axis II disorders and the subsequent treatment options. Objective: To study the effects of combined treatment of Axis I and Axis II disorders compared to the treatment of only Axis I or Axis II disorder on the short and long term. Design: Multi-center randomized controlled clinical trial with repeated measurements at baseline (M0), midtreatment (M5) posttreatment (M10) and follow-up M(6) and M(12) after baseline.Procedure: Adult patients with an Axis I anxiety disorder as primary diagnosis and a comorbid Axis II Cluster C personality disorder drawn from the different outpatient clinics of Adhesie in Deventer and Almelo and from several outpatient branches of the HSK-Group in the Netherlands will be invited to participate. Interventions: In treating Axis I anxiety disorder the recommendations of the Dutch guideline for Anxiety disorders will be followed. Treatment will consists of maximally 30 sessions of cognitive-behavioral therapy. For the treatment of the Cluster C personality disorders a protocol for schema focused cognitive therapy will be used (maximally 30 sessions). Combined treatment will consist of treatment of anxiety disorders (15 sessions) followed by treatment of the cluster C personality disorder (15 sessions). -Outcome measures: The level of anxiety as assessed with the BAI constitutes the primary outcome measure, Secondary outcome measures will assess: more specific forms of anxiety (PSWQ, ASI, FQ, LSAS, PI-R), general psychopathology (SCL-90R), interpersonal problems (IIP), personality pathology (ADP-IV, NEO-PI-R), cognitive schemas and schema modes (SV-1, SMI-R), quality of life (WHOQOL-Bref, EQ-6D), direct and indirect costs (TIC-P) and patient satisfaction (GGZ-thermometer). Remission from anxiety and Axis II disorder is measured with the MINI and the SCID-II at posttreatment and at follow up. To evaluate the efficacy of the treatment modalities a kost analysis will be performed using data from a medical consumption diary kept by the patient.Data-analysis/power: The proposed study will be powered in order to be able to detect a clinically relevant effect on the primary outcome measure with a medium effects size. Assuming a medium effect (delta = .75) of the combined treatment compared to one of the mono-treatments with a power of 80% and alpha set at .05, 35 patients per study arm have to be included. Assuming a dropout rate of maximally 30%, at least 46 patients per study arm (138 patients in total) will have to be included in the trial.Time schedule: M 1-3 preparations, M 4- 44 screening and treatment, M 9 49 midtreatment measurement, M 14-54 post-test,M 20-60 follow-up 6 monthsM 26-66 follow-up 12 months, M 66-72 analyses, interpretation, publications.

Related organisations

Secretariat Clinical Psychology (UL)
Financier ZonMw

Related people

Project leader Prof.dr. Ph. Spinhoven


D23350 Psychiatry, clinical psychology
D51000 Psychology

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