Abstract
Background We have established an epidemiological obsessive-compulsive disorder (OCD) cohort in Sweden. Individuals contributed DNA for genotyping and sequencing and also completed a Swedish translation of the Obsessive-Compulsive Inventory-Revised (OCI-R), a self-report questionnaire for assessing the severity and type of symptoms of OCD. This study made use of the OCI-R data to examine the severity and symptom dimensions of OCD as well as comorbidity with other psychiatric disorders.
Methods OCI-R data for 1,134 individuals were available for this study, 1,010 diagnosed with OCD, and 124 diagnosed with chronic tic disorders without OCD used as a comparison group. We first evaluated the psychometric properties of the Swedish translation of the OCI-R. Then, we linked data from the Swedish national registries to access and analyze psychiatric comorbidities of OCD.
Results The Swedish translation of OCI-R demonstrated internal consistency (Cronbach’s α = 0.9) 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%). 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 compared to individuals with no psychiatric comorbidity.
Conclusion We showed that the Swedish translation of the OCI-R has appropriate psychometric properties. Using an epidemiological framework, we were able to assess the severity and symptom dimensions of OCD and comorbidity with other psychiatric disorders.
Competing Interest Statement
The authors have declared no competing interest.
Funding Statement
This study was supported by a grant from the Beatrice and Samuel A. Seaver Foundation (DEG, JDB, BM); the Mindworks Charitable Lead Trust (DEG); the Stanley Center for Psychiatric Research (DEG); NIMH R01MH124679 (DEG).
Author Declarations
I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.
Yes
The details of the IRB/oversight body that provided approval or exemption for the research described are given below:
Ethical approval was obtained from the Institutional Review Board at the Icahn School of Medicine at Mount Sinai, New York, USA, and the Regional Ethical Review Board in Stockholm, Sweden.
All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.
Yes
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Yes
Footnotes
Declarations of interest: none
Data Availability
Study data are maintained at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden. Extracted DNA samples are stored at Karolinska Biobank [https ://ki.se/en/resea rch/ki-bioba nk]. Biological samples can be made available to approved researchers. EGOS informed consents permit sharing of genetic data via the database of Genotypes and Phenotypes (dbGaP).