Development and initial validation of the obsessive beliefs questionnaire and the interpretation of intrusions inventory

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Abstract

In 1995 the Obsessive Compulsive Cognitions Working Group initiated a collective process to develop two measures of cognition relevant to current cognitive–behavioural models of OCD. An earlier report (Behav. Res. Therapy, 35 (1997) 667) describes the original process of defining relevant domains. This article describes the subsequent steps of the development and validation process: item generation, scale reduction, and initial examination of reliability and validity. Two scales were developed. The Obsessive Beliefs Questionnaire consists of 87 items representing dysfunctional assumptions covering six domains: overestimation of threat, tolerance of uncertainty, importance of thoughts, control of thoughts, responsibility, and perfectionism. The Interpretation of Intrusions Inventory consists of 31 items that refer to interpretations of intrusions that have occurred recently. Three of the above domains are represented: importance of thoughts, control of thoughts, and responsibility. The item reduction and validation analyses were conducted on clinical and non-clinical samples from multiple sites. Initial examination of reliability and validity indicates excellent internal consistency and stability and encouraging evidence of validity. However, high correlations indicating overlap between some of the scales, particularly importance of thoughts, control of thoughts, and responsibility will need to be addressed in subsequent empirical and theoretical investigations.

Section snippets

Initial development of the OBQ and III

The development of the two cognitive measures described in this paper was driven by recent cognitive models hypothesizing the importance of appraisals (interpretations) of intrusive thoughts (obsessions) and of beliefs (assumptions, attitudes) regarding several realms in generating and maintaining OCD symptoms. Cognitive models for OCD have been articulated by Salkovskis, 1985, Salkovskis, 1989, Rachman, 1993, Rachman, 1997 and Freeston, Rheaume, and Ladouceur (1996) and Clark and Purdon (1993)

Participants

Participant volunteers were recruited at ten different sites. A summary of sites and samples is provided in Table 1. Three types of samples were sought: 1) people with OCD, 2) people with anxiety disorders but not OCD, and 3) non-clinical controls (community members and students). Criteria for inclusion in the OCD group were a diagnosis of OCD (according to DSM–IV; American Psychiatric Association, 1994) and absence of psychosis and substance abuse. Overall, 101 people with OCD, 374 student

Method

The participants and measures were the same as described previously for the scale construction. Because it can be difficult to interpret findings from scales using negative numbers, we transformed the OBQ item scale (originally ranging from −3 to +3) to a 1 to 7 scale. Likewise, the 0 to 100 scale for III items was also transformed arithmetically by dividing the total score by 10 to provide more familiar total scores ranging from 0 to 310. Such transformations have no effect on scale

Discussion

This paper describes the development and initial validation of two scales measuring assumptions and interpretations relevant to current cognitive–behavioural models of OCD. The initial step sought to maximise content validity by drawing on an international panel of experts who used a rigorous process to first identify and define key dimensions and then generate relevant items. The subsequent step reduced the item pool based on findings from both clinical and non-clinical samples to obtain high

Acknowledgements

The Padua meeting (September 1997) and parts of this study were supported by an unrestricted grant from Solvay Pharmaceuticals.

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Corresponding author: Gail Steketee (Scales and translated versions are available from the corresponding author. Tel.: +1-617-353-3750; fax: +1-617-353-5612. [email protected] (G. Steketee).

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Co-chairs: Gail Steketee and Randy Frost.The members of the working group who contributed to this study are (in alphabetical order): Nader Amir, Martine Bouvard, Cheryl Carmin, David A. Clark, Jean Cottraux, Paul Emmelkamp, Elizabeth Forrester, Mark Freeston, Randy Frost, Rense Hoekstra, Michael Kyrios, Robert Ladouceur, Fugen Neziroglu, Gilbert Pinard, C. Alec Pollard, Christine Purdon, S. Rachman, Josee Rheaume, Candida Richards, Paul Salkovskis, Ezio Sanavio, Roz Shafran, Claudio Sica, Gregoris Simos, Ingrid Sochting, Debbie Sookman, Gail Steketee, Steven Taylor, Dana Thordarson, Patricia van Oppen, Ricks Warren, Maureen Whittal, Jose Yaryura–Tobias. Special thanks to Steven Taylor who conducted the main analyses of the data and to Mark Freeston for drafting the manuscript.

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