The assessment of obsessionality using the Padua inventory: its validity in a British non-clinical sample

The Padua Inventory (PI) is a measure of obsessive–compulsive phenomena, which permits measurement of both number and severity of symptoms. Data is available from Italy, the US, the Netherlands and Australia on non-clinical samples. The present study provides a psychometric evaluation of the PI on a British non-clinical sample (N=1855). Comparisons are made with other data and further suggestions for the use of the PI are made. Results from the present study indicate that the PI has similar, though not identical, factor structure to previous studies, adequate internal reliability and construct validity. Four factors emerged, containing clusters of items broadly relating to ‘impaired control over mental activities/doubtingʹ, ‘contaminationʹ, ‘checkingʹ and ‘worries about losing control over motor behaviourʹ and these included most of the items loading on the same factors in earlier studies together with additional items. The relationships of age and gender with the PI scores are investigated. Differences were found from the Sanavio (1988) [Sanavio, E. (1988). Obsessions and compulsions: the Padua Inventory. Behaviour Research and Therapy, 26, 169–177.] Italian sample. These differences are in keeping with other available data from British samples and other data on the epidemiology of Obsessive Compulsive Disorder. The five factor structure found in the one study using clinical and non-clinical subjects is discussed in relation to the present analyses.