Clinical relevance of comorbidity in obsessive compulsive disorder: the Netherlands OCD Association study.

Background: This study describes lifetime and current rates of comorbidity, its onset and its consequences in a large clinical sample of patients with obsessive compulsive disorder (OCD). A wide range of risk factors and clinical characteristics were also examined to determine whether pure OCD is different from OCD with current comorbidity. Finally, the temporal sequencing of the disorders was examined.
Method: Data were obtained from the Netherlands Obsessive Compulsive Disorder Association (NOCDA) study. A sample of 382 participants with current OCD (during the past month) was evaluated.
Results: Current comorbidity occurred in 55% of patients with OCD, while 78% suffered from lifetime comorbidity. Comorbidity is associated with more severe OCD, anxiety and depressive symptoms and more negative consequences on daily life. Multiple comorbid disorders often precede OCD and influence both its course and severity. Childhood trauma and neuroticism are vulnerability factors for the development of multiple comorbid disorders in OCD.
Limitations: It should be noted that causal inferences about the association between risk factors and OCD are precluded since our results were based on cross-sectional data.
Conclusion: (Multiple) comorbidity in OCD is clinically relevant since it is associated with a specific pattern of vulnerability, with greater chronicity, with more severe OCD and more negative consequences on daily life. This indicates that the diagnosis and treatment of all comorbid disorders is clinically relevant, and clinicians should be especially aware of multiple disorders in cases of childhood trauma and high levels of neuroticism. Primary OCD has a different developmental and comorbidity pattern compared to secondary OCD.
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