Second-Order Factor Structure of the Vancouver Obsessive Compulsive Inventory (VOCI) in a Non-Clinical Sample

Abstract

Background: The Vancouver Obsessive Compulsive Inventory (VOCI) is a self-report measure of the severity of obsessive-compulsive problems such as contamination, checking, obsessions, hoarding, needing things to be just right, and indecisiveness. In the seminal paper a six-correlated-factor structure was found in a sample of OC patients, but the issue of the factor structure of the VOCI in non-clinical populations was not addressed. Aim: This study assesses the psychometric properties and the factor structure of the Italian version of the VOCI in a non-clinical sample. Method: The VOCI was administered to a large community sample (n = 445). Some participants also completed a battery including measures of OC behaviour, worry, anxiety and depression (n = 89) and were administered the VOCI twice at an 8-week interval (n = 46). Results: Confirmatory factor analyses replicated the six-correlated-factor structure originally found in a patient sample, but a more parsimonious, second-order-factor model showed a statistically higher fit, suggesting that VOCI subscales can be considered as facets of a higher-order OCD factor. The whole item pool and each of the subscales showed good internal consistency, unidimensionality, test-retest reliability and convergent construct validity. As in the original version, limited support for discriminant validity was found. Scores were weakly associated with age, gender and education. Conclusions: Although some key issues still need to be investigated (e.g. sensitivity to change), the VOCI seems to be a psychometrically sound instrument for the assessment of OCD-related behaviours and thoughts and can be used in cultural contexts different from the original.