(PS2-D97) Predicting Symptom Prognoses Among Individuals with Primary OCD vs. PTSD Diagnosis

Background: Obsessive-compulsive disorder (OCD) is a psychiatric illness affecting approximately 1.2% of the U.S. population and is characterized by obsessions or compulsions. Posttraumatic stress disorder (PTSD) impacts approximately 3.6% of the U.S. population. It is characterized by symptoms of intrusion, avoidance, hyperarousal, and negative changes in mood and cognition. The intrusive and repetitive thoughts that induce distress comprise a hallmark component of both OCD and PTSD. This study evaluated the extent to which treatment targeting OCD results in significant improvement in PTSD symptoms and vice versa.

Method: Data were collected by administering self-report measures online to treatment-seeking individuals (n=331) at an outpatient clinic between 2015 and 2018. Treatment plan comprised of 10 to 20 sessions of exposure therapy, including prolonged exposure (PE) and exposure and response prevention (EX/RP). Posttraumatic Diagnostic Scale (PDS-5), a 24-item self-report measure, was utilized to evaluate PTSD symptoms in the last month. Obsessive Compulsive Inventory – Revised (OCI-R), an 18-item measure, was used to assess OCD symptoms. PDS-5 and OCI-R were administered at three different time points: intake, mid-treatment, and post-treatment. Multi-level linear regression was utilized to examine the time-lagged predictive effect of OCD symptoms on PTSD symptoms, and conversely PTSD symptoms on OCD symptoms.

Results: For all clinic patients, PTSD symptoms in the prior observation predicted OCD symptoms in the subsequent observations. OCD symptoms in the previous observation also predicted the next-observation PTSD symptoms. When the sample was restricted to include patients with principal PTSD, the same pattern emerged (n=85). Symptoms of PTSD predicted the next wave OCD symptoms while the OCD symptoms predicted the next wave PTSD symptoms. However, although PTSD symptoms predicted next-phase OCD symptoms among patients with OCD as their primary diagnosis (n=93), OCD symptoms did not predict the next-phase PTSD symptoms.

Discussion: Findings suggested that PE, a treatment aimed to reduce PTSD symptoms, also subsequently lessened OCD symptoms among patients with the primary PTSD diagnosis and comorbid OCD. In contrast, EX/RP, a treatment targeting OCD symptoms, did not reduce PTSD symptoms among patients with primary OCD diagnosis and comorbid PTSD. Overall, clinicians should critically assess PTSD comorbidity among patients with primary OCD diagnosis. Moreover, OCD treatment should be supplemented with PTSD treatment when comorbid conditions are present.