Obsessive-Compulsive Disorder: Epidemiology, Demographic Characteristics

Epidemiology

The ECA study found that OCD was the fourth most common psychiatric disorder (after the phobias, substance use disorders and major depressive disorder), with a prevalence of 1.6% over 6 months and a lifetime prevalence of 2.5% (Myers et al., 1984; Robins et al., 1984). Although the ECA survey has been criticized as overestimating OCD’s prevalence a subsequent study in the USA and several epidemiological studies in other countries have supported its findings. The National Comorbidity Survey Replication (NCS-R) found the lifetime prevalence for OCD to be 1.6% (Kessler et al., 2005). Using the same instrument as the ECA, studies have been done in diverse cultures, including Puerto Rico, Canada, Germany, Taiwan, New Zealand and Korea, as part of the Cross National Collaborative Group (Weissman et al., 1994). The lifetime (range 1.9–2.5%) and annual (range 1.1–1.8%) prevalence rates of OCD were remarkably consistent across countries with the exception of Taiwan. The rates in Taiwan were substantially lower than in all the other sites, paralleling Taiwan’s low rates of other psychiatric disorders.

Demographic Characteristics

Gender Distribution

Women appear to develop OCD slightly more frequently than do men. A pooled sample from two studies with a total of 991 subjects found that 52% of the subjects were women. However, a study that assessed the presence of comorbid disorders characterized by psychosis (schizophrenia, delusional disorder) or psychosis-like features (schizotypal personality disorder) in 475 patients with OCD found a different sex ratio. Fifty-six percent of the patients with OCD who did not have one of these comorbid disorders were women, whereas 85% of those with one of these comorbid disorders were men. A predominance of males has also been observed in child and adolescent OCD populations. In a study of 70 probands with OCD who were aged 6 to 18 years, 67% were males. This finding may be due to the fact that males develop OCD at a younger age than do females.

Marital Status

Although marital status was not found to be a predictor of course in a number of earlier studies, a recent prospective study of 107 subjects with OCD found that being married significantly increased the probability of partial remission, with married patients more than twice as likely to remit as unmarried ones (Steketee et al., 1999).