[Washing, checking, and rumination: are the belief domains, obsessions and compulsions specific to OCD subtypes?]

Abstract

Aim of the study: The aim of the present study is to explore the validity of the Padua inventory and two belief questionnaires: the obsessive beliefs questionnaire (OBQ) and the interpretation of intrusions inventory (III).

Background: The Padua inventory is a 60-item self-report measurement of obsessive compulsive symptoms that measures both classic compulsive checking and cleaning behaviour as well as various types of obsessions, including impulses. Studies in several countries have provided support for the reliability and validity of the Padua inventory, including Italy, the Netherlands, North America, and the UK. The obsessive beliefs questionnaire assesses belief domains related to obsessive compulsive disorder (OCD): inflated responsibility, importance of thoughts, control of thoughts, overestimation of threat, perfectionism, and intolerance of uncertainty. It consists of 87 items representing dysfunctional assumptions covering these six domains. 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. Data from clinical or non-clinical samples are used to study the factor structure, reliability, and convergent and divergent validity of these two questionnaires.

Methodology: The three questionnaires were administrated to two groups of people as follows: 96 patients with OCD and 53 non-clinical subjects. The patients were selected from Rhone Alpes clinics and hospitals using DSM-IV criteria for diagnosis, prior to treatment. Diagnosis was based on semi-structured interview (MINI) and clinical interview by a trained psychiatrist using DSM-IV criteria. The second aim of the study was to investigate generality and congruence criterion of the subscales of the Padua inventory and beliefs domains in OCD symptom subtypes (rumination, washing, checking). The present study investigates whether specific OCD symptom subtypes are associated with specific symptom subscales and belief domains in an OCD sample. The criteria for categorizing a participant into an OCD symptom subtype was a score greater or equal to 75% of one main ritual. Fifty participants (52%) met these criteria: washing (n=20), rumination (n=16), checking (n=8), hoarding (n=1), perfectionism (n=3), and repeating (n=2). The other 46 subjects formed a non-specific symptom subtype (two or more rituals). Participants in the precision (perfectionism), the hoarding, and repeating symptom subtypes were excluded because of a small sample.

Results: The Padua inventory and the two questionnaires OBQ and III discriminated between French OCD and non clinical controls. In the OCD sample, the three subtypes (washers, rumination and checkers) did not differ from each other on total YBOCS score and total Padua score. The "washer" subjects scored higher than both "checker" subjects and subjects with rumination on the washing scale of the Padua inventory. The "checker" subjects scored higher than the two other subtypes on the checking scale. The impaired mental control and urges and worries of losing control scales failed to discriminate between the subjects with rumination and the two other (checking and washing) subtypes. The OBQ total and the six subscale scores failed to discriminate between the three OCD subtypes. These results were replicated with the III. The ANOVAs revealed that the participants in the rumination symptom subtype scored higher only on the importance/control of thoughts of the OBQ-44 than the participants in the checking subtype. Implications for future research are discussed.