Does a unique co-occurring OCD and PTSD factor structure exist?: Examination of overlapping OCD and PTSD symptom clusters

OCD and PTSD share many commonalities, including phenotypic and functional overlap in symptoms. Specifically, both disorders are characterized by unwanted, intrusive, anxiety/distress-eliciting intrusive thoughts and evoking behaviors intended to control, neutralize, suppress, or outright avoid intrusive thoughts and associated anxiety/distress. Extant factor analytic research supports a model of PTSD at odds with current DSM-5 criteria, and no examination of the factor structure of comorbid OCD+PTSD currently exists despite the noted overlap in symptomatology and high rates of comorbidity. Using a sample of 4073 patients diagnosed with OCD and/or PTSD enrolled in intensive treatment programs for OCD or PTSD, multigroup confirmatory factor analysis (MGCFA) and measurement invariance tests were run to determine the best fitting model of OCD and PTSD symptoms in patients with OCD+PTSD. Four models were compared across patients with OCD, PTSD, and OCD+PTSD: DSM-5 and 7-factor hybrid PTSD models with OCD symptoms structured as either combined or comorbid constructs. The comorbid hybrid model proved the best fit, and both hybrid models evidenced better fit than DSM-5 models. The current study lends additional support for the hybrid model of PTSD and suggests that there is no existence of a unique factor structure of OCD and PTSD symptoms in individuals with the comorbid conditions.