The aim of this study was to determine the prevalence of co-morbidity with obsessive-compulsive disorder (OCD) among bipolar disorder (BD) patients in order to assess the impact of OCD on the socio-demographic and clinical features of patients in a highly endogamous population. A cohort study was carried out on 396 patients enrolled between November 2011 to October 2013. We employed the WHO Composite International Diagnostic Interview (WHO-CIDI) and Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-IV/Clinical Version for diagnoses, the Yale-Brown Obsessive Compulsive Scale Symptom Checklist for scoring OCD. Patients were grouped in BD patients with OCD (BD-OCD) and BD patients without OCD.

Groups were compared for socio-demographic and clinical variables. There were no significant differences for age, gender, BMI, and marital status, between BD patients with and without OCD. We found significant differences in level of education (P = 0.022), occupation status (P = 0.025), household income, (P = 0.049), cigarette smoking (P = 0.038), sheesha smoking (P = 0.007), and prevalence of consanguinity (P = 0.036) among these groups. Number of hospitalizations and Young Mania Rating Scale score were not different among BD patients with or without OCD whereas there were significant differences in Hamilton-Depression score, Clinical Global Impression-BD Score, duration of illnesses, and Global Assessment of Functioning (GAF). Also specific phobia, somatization, depression, mania, any mood disorder, oppositional defiant disorder, ADHD and personality disorder were more common in BD than OCD–BD group. This study confirms that BD-OCD is a common co-morbidity, largely under-recognized in clinical practice, which may significantly change BD presentation and outcome.