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Original Research

Does the Therapy Manual or the Therapist Matter Most in Treatment of Obsessive-Compulsive Disorder? A Randomized Controlled Trial of Exposure With Response or Ritual Prevention in 118 Patients

Patricia van Oppen, PhD; Anton J. L. M. van Balkom, MD, PhD; Johannes H. Smit, PhD; Josien Schuurmans, PhD; Richard van Dyck, MD, PhD; and Paul M. G. Emmelkamp, PhD

Published: March 23, 2010

Article Abstract

Background: The importance of the therapist’s education and experience for the successful behavior treatment of obsessive-compulsive disorder (OCD) has not been investigated. Data on the relative effectiveness of self-controlled versus therapist-controlled in vivo exposure with response or ritual prevention (ERP) have yielded conflicting results. The present study compared the effectiveness of 4 different modes of delivery of ERP in a referred sample of OCD patients.

Method: Of the 146 eligible OCD outpatients, 118 patients enrolled in this randomized controlled trial and were randomly assigned to (1) therapist-controlled ERP performed by experienced behavior therapists; (2) therapist-controlled ERP performed by master’s students of clinical psychology; (3) self-controlled ERP performed by experienced behavior therapists; and (4) self-controlled ERP performed by master’s students of clinical psychology. This trial was performed from January 1999 to January 2005.

Results: Our analyses revealed no significant differences in clinical outcome between any of the different modes of delivery of ERP at posttreatment. The different ERP modes of delivery were associated with significant pretreatment to posttreatment improvement on all measurements, with large effect sizes on the primary outcome measure, the Yale-Brown Obsessive Compulsive Scale.

Conclusions: Our results indicate that clinically inexperienced master’s students with no postgraduate training can be as capable as experienced and certified behavior therapists in treating OCD patients, as long as therapists adhere to a standardized treatment manual and adequate training and supervision is provided. In contrast to other studies, we did not find a supposed benefit of therapist-controlled ERP versus self-controlled ERP in patients with OCD.

Trial registration: Identifier: NTR1444

J Clin Psychiatry

Submitted: December 24, 2008; accepted March 20, 2009.

Online ahead of print: March 23, 2010 (doi:10.4088/JCP.08m04990blu).

Corresponding author: Patricia van Oppen, PhD, GGZ InGeest/VU Medical Center Academic Anxiety Outpatient Clinic, A.J. Ernststraat 887, 1081 HL Amsterdam, The Netherlands (

Volume: 71

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