Degree Date



Doctor of Philosophy (PhD)




This study explored the impact of significant comorbid trauma symptomatology on obsessive-compulsive disorder (OCD) symptom severity and cognitive-behavioral therapy (CBT) outcome. A retrospective chart analysis was performed on pre-treatment and post-treatment measures for 78 patients seen for primary OCD at a specialty anxiety clinic, roughly half of whom (n = 38) also presented with significant trauma symptoms (meeting criteria for partial PTSD). Results revealed that the presence of comorbid trauma did not differentiate between patient groups with regard to OCD symptom severity, although it did predict a higher rate of treatment dropout and lower treatment response when a reduction of > 25% in mean Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) score was used as the criterion but not when a reduction of > 35% was used. There was no significant difference between OCD patients with and without concurrent trauma symptoms with regard to remission status (Y-BOCS score reduction > 50% plus a post-treatment Y-BOCS score of < 14). On average, treatment completers in both groups experienced a significant drop in OCD symptom severity, with a mean Y-BOCS score reduction of 40% in the trauma group and 49% in the group without trauma. Neither the number of comorbid disorders nor the presence of specific comorbid conditions was predictive of OCD treatment outcome; however, patients with comorbid trauma symptomatology endorsed significantly more symptoms of other anxiety disorders in addition to significantly greater impairment stemming from these symptoms than did patients without a history of trauma. Findings are discussed in terms of the implications for the assessment and treatment of OCD with comorbidity.


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