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
06 / 2008 - unknown
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.