Background and purpose: The age of the onset of obsessive-compulsive disorder (OCD) and its manifestation is now identified at childhood. In the present study, we aimed to epidemiologically assess OCD and its main determinants in school-age children. 

Materials and Methods: This cross-sectional study was performed on 600 consecutive schoolage children (7-12 years old) in primary schools at Kermanshah, Iran in May 2012. OCD status was assessed using the Maudsley Obsessive Compulsive Inventory.

Results: In this study, the prevalence of OCD in children were 12.2% (73 person). Among OCDs, 32.0% were male and 68.0% were female with a significant difference (P < 0.001). Among different subscales of OCD, checking was more prevalent in girls than in boys (74.0% vs. 65.0%, P < 0.001), whereas doubting was more revealed in boys than in girls (56.0% vs. 34.0%, P < 0.001). In this regard, no differences were found between boys and girls in the rate of washing subscale (43.0% vs. 40.0%, P = 0.456) and slowness domain (30.0% vs. 34.0%, P = 0.294). Totally, mean MOCI score was significantly a higher in girls than in boys in different grades of education. OCD was influenced by father’s occupation status, parents’ education level, order of birth, dependence to mothers and previous history of OCD in fathers.
Conclusion: The prevalence of OCD was a higher than other areas in the country and other populations. Because of the existence of OCD potential determinants including socioeconomic level and familial tendency, the high prevalence of the disease must be considered in correlation with these factors.