Psychometric properties of the Swedish translation of the Obsessive-Compulsive Inventory-Revised and the population characteristics of the symptom dimensions of OCD

Purpose EGOS is an epidemiological obsessive-compulsive disorder (OCD) cohort in Sweden. Individuals contributed DNA for genotyping and sequencing and completed a Swedish translation of the Obsessive-Compulsive Inventory-Revised (OCI-R), a self-report questionnaire for assessing the severity of OCD. This study aimed first to evaluate the psychometric properties of the Swedish translation of the OCI-R and then shed light on the frequency, severity, and symptom dimensions of OCD comorbid with other psychiatric disorders. Methods OCI-R data were available for 1010 individuals diagnosed with OCD, and 124 individuals diagnosed with chronic tic disorders without OCD used as a comparison group. We first performed a confirmatory factor analysis to confirm the six-factor structure of OCI-R. Then, we estimated Cronbach's alpha coefficient and the generalizability coefficient to evaluate the internal consistency of the OCI-R. We linked the data from the Swedish national registries to access and analyze psychiatric comorbidities of OCD. Results The Swedish translation of OCI-R demonstrated internal consistency and clear agreement with the OCI-R six-factor model. The mean total OCI-R score for females was significantly higher than for males. The most comorbid psychiatric condition to OCD were anxiety disorders (13.6%) and major depression (12%). Conclusion The Swedish translation of OCI-R was a valid and reliable measure for assessing the severity of OCD. We observed that individuals with OCD frequently had additional comorbid psychiatric disorders and that the severity of OCD was significantly higher in individuals with at least one additional psychiatric comorbidity as compared to individuals with no psychiatric comorbidity.

Automated summary

This study evaluated the psychometric properties of the Swedish translation of the Obsessive-Compulsive Inventory-Revised (OCI-R) and explored the frequency, severity, and symptom dimensions of OCD comorbid with other psychiatric disorders. The results showed that the Swedish translation of OCI-R had good internal consistency and clear agreement with the six-factor model. Females had significantly higher total scores on the OCI-R compared to males. The most common psychiatric comorbidities with OCD were anxiety disorders and major depression.