Psychometric validation of the Obsessive Beliefs Questionnaire and the Interpretation of Intrusions Inventory: Part I

Abstract

This article reports on the validation of the Obsessive Beliefs Questionnaire (OBQ) and Interpretations of Intrusions Inventory (III) developed by the Obsessive Compulsive Cognitions Working Group (OCCWG) to assess the primary beliefs and appraisals considered critical to the pathogenesis of obsessions. A battery of questionnaires that assessed symptoms of anxiety, depression, obsessive–compulsive symptoms and worry was administered to 248 outpatients with a DSM-IV diagnosis of Obsessive–Compulsive Disorder (OCD), 105 non-obsessional anxious patients, 87 non-clinical adults from the community, and 291 undergraduate students. Tests of internal consistency and test–retest reliability indicated that the OBQ and III assessed stable aspects of OC-related thinking. Between-group differences and correlations with existing measures of OC symptoms indicated that the OBQ and III assess core cognitive features of obsessionality. However, the various subscales of the OBQ and III are highly correlated, and both measures evidenced low discriminant validity. The findings are discussed in terms of the relevance and specificity of cognitive constructs like responsibility, control and importance of thoughts, overestimated threat, tolerance of uncertainty and perfectionism for OCD.

Introduction

In the last decade theory, research and treatment of Obsessive–Compulsive Disorder (OCD) has increasingly turned to cognitive structures, processes and content to understand the etiology and persistence of obsessions and compulsions. Cognitive behavioral theories and interventions developed and elaborated by several investigators (Clark and Purdon, 1993, Freeston, Rheaume and Ladouceur, 1996, van Oppen and Arntz, 1994, Rachman, 1997, Rachman, 1998, Salkovskis, 1985, Salkovskis, 1989, Sookman, Pinard and Beauchemin, 1994) provided an impetus for further interest in the cognitive basis of OCD. Although differing in emphasis, each of these approaches recognized that a critical element in the pathogenesis of obsessions, in particular, was the meaning that the obsession had to the person suffering from OCD. Individuals at risk for OCD are thought to endorse certain predisposing, enduring self-referent schematic content, or beliefs, that when activated by the occurrence of particular unwanted mental intrusions, lead to faulty appraisals or misinterpretations of the unwanted intrusive thought or obsession. The faulty appraisals, in turn, evoke efforts to control the thought or neutralize the distress associated with the obsession, often by the performance of compulsive rituals. Thus, the faulty misinterpretation of the intrusion is considered a central process leading to the unusual persistence and salience of obsessional content in OCD.

Any new scientific approach to a psychological disorder requires that the key concepts and processes implicated in that perspective must be clearly articulated and amenable to measurement and experimentation. Cognitive constructs such as inflated responsibility, overestimated threat and consequences of the obsession, exaggerated importance and control of thoughts, thought–action fusion, perfectionism, intolerance of uncertainty, and misinterpretation of personal significance were proposed as critical elements of the cognitive basis of OCD (for reviews see Freeston, Rheaume and Ladouceur, 1996, Frost and Steketee, 2002, Purdon, 2001). In addition, refinements of Cognitive Behavioral Treatment (CBT) of OCD were based on the modification of key beliefs and appraisals formulated in cognitive behavioral theories (van Oppen and Emmelkamp, 2000, Rachman, 1998, Salkovskis and Warwick, 1985, Whittal and McLean, 1999). However, two problems became apparent with this shift to cognitive theory and practice in OCD. First, there was no consensus amongst CBT researchers about which cognitive constructs were crucial to understanding obsessions or how these concepts should be defined. And second, numerous self-report measures were developed that claimed to assess obsessional beliefs and appraisals (see review by Taylor, Kyrios, Thordarson, Steketee, & Frost, 2002). However, most had weak and inconsistent psychometric status which resulted in considerable measurement error in studies on cognition in OCD.

To rectify this situation, in 1995 an international group of researchers formed the Obsessive Compulsive Cognitions Working Group (OCCWG) with the intent to develop specific operational definitions of the critical cognitive constructs of OCD and to construct self-report instruments of obsessional beliefs and appraisals of intrusions that would benefit from the combined expertise of a broadly based group of cognitively oriented OCD researchers. The first objective of the group was achieved with publication of the first OCCWG paper in 1997. In this paper six core cognitive domains were identified: (a) overestimation of threat, (b) intolerance of uncertainty, (c) importance of thoughts, (d) control of thoughts, (e) responsibility, and (f) perfectionism. Specific characteristics or elements of each cognitive dimension were described and a pool of questionnaire items written to assess each of the six domains based on the criteria and characteristics identified by the group. This led to an initial version of two cognitive questionnaires for OCD, the Obsessive Beliefs Questionnaire (OBQ) and the interpretation of intrusions inventory (III). The OBQ was intended as a measure of enduring, predisposing beliefs that may increase risk for OCD, whereas the III was developed to assess the specific appraisals of responsibility, overimportance of thought intrusions and control of intrusions that were considered instrumental in the persistence of obsessions.

The development of a 127-item pool for the OBQ and a 43-item pool for the III constituted the first stage of this collaborative enterprise. The history and development of these instruments can be found in the group’s first publication (OCCWG, 1997), as well as a review provided by Taylor, Kyrios, Thordarson, Steketee, & Frost (2002). The second stage of the OCCWG research involved collection of data on this preliminary version of the OBQ and III. The OBQ-127 and III-43 were administered to 101 people with a primary diagnosis of OCD, 374 university students, 76 non-clinical English-speaking community adults, 12 non-OCD anxious patients and 35 Greek-speaking non-clinical controls. Participants were recruited from 10 different sites in the US, Canada, Australia and Greece. In addition other self-report measures of OC, depressive and anxious symptoms were administered to assess concurrent and discriminant validity. Exploratory item analysis revealed a number of weak and unreliable items in both instruments resulting in a final 87-item OBQ and 31-item III. The six subscales of OBQ-87 and the three subscales of III-31 had good internal consistency, but were very highly intercorrelated. Group comparisons indicated that the OCD patients scored significantly higher than non-clinical and anxious controls on all the OBQ and III subscales. Furthermore the two OC cognition measures showed a stronger relationship with the Padua inventory total score after partialling out depressive and anxious symptoms than they did with the total scores of the Beck depression or Beck anxiety inventories after controlling for obsessional symptoms. Lower correlations were found between the OBQ and III subscales, and the impulses of harming self or others, contamination and washing compulsions, and dressing and grooming subscales of the Padua inventory. As expected, this suggests that the OBQ and III are more applicable to obsessive than compulsive symptomatology, although the measures may not be as relevant for certain subtypes of OCD such as compulsive washers. Nevertheless, these data provide preliminary evidence for the reliability and validity of the OBQ-87 and the III-31 (for a complete report see OCCWG, 2001).

Despite these initial encouraging findings, a number of unresolved issues required a full scale validation study of the OBQ-87 and III-31. Examination of test–retest reliability was necessary to establish the reliability of the two instruments, and a larger non-OCD anxious comparison group was needed to determine their specificity. In addition, the high overlap apparent among the OBQ and III subscales required further investigation. Finally, more participants were needed to conduct a factor analysis which will be reported in a companion paper. The present study was initiated to collect these critical data on the OBQ-87 and III-31, along with other standardized measures of obsessional, anxious and depressive symptoms and cognitions. Findings from the present study are reported in two parts. In this paper we report on the reliability, and convergent and discriminant validity of the six subscales of the OBQ and three subscales of the III. A companion paper examines the factor structure and presents findings on reduced subscales based on the factor solution for the OBQ-87 and III-31.