From OCD-UK.org

• Around the world there are literally millions of people affected by OCD and it is considered to be the fourth most common mental illness in many western countries that will affect men, women and children regardless of their race, religion, nationality or socio-economic group.
• In the United Kingdom current estimates suggest that 1.2% of the population will have OCD, which equates to 12 out of every 1000 people, and based on the current estimates for the UK population, these statistics mean that potentially, approximately 741,504 people are living with OCD at any one time.

These estimates are still considered to be underestimated with many people affected by OCD still suffering in silence through embarrassment and fear of being labelled. Others are unaware that their suffering is a recognised medical condition.

From OCDaction.org

• There is an average delay of 12 years between the onset of OCD and treatment being received. There are many reasons why people with OCD delay seeking help. These include a fear that they will be committed to a secure institution, a fear of the stigma associated with mental health disorders or a simple belief that no one can help them.

From Overcoming Obsessive Compulsive Disorders

• OCD is in the Top 10 most handicapping illnesses as calculated by the World Health Organisation in terms of lost income and decreased quality of life.
• It is the fourth most common mental disorder after depression, alcohol and substance abuse, and social phobia.
• At least 1 in every 100 of the adult population who significantly distressed and handicapped by their OCD, along with about 1 in every 200 children and adolescents.
• Young children with OCD are twice as likely to be boys as to be girls.
• The average age of onset is in the early twenties. It is slightly earlier for men, who tend to develop OCD in the late teens, than for women, in whom it tends to emerge in the mid-twenties.
• One reason why the level of OCD has been underestimated in the past is that people with OCD are often too afraid or too ashamed to seek help. Often individuals with OCD struggle on by themselves for 10-15 years before they seek professional help. There is a variety of reasons for this reluctance@ many individuals with OCD worry that other people will think they are crazy, do not know that their disorder is a recognisable condition, or think that they should just be able to pull themselves together.