Using data from Danish registers, we conducted a nationwide prospective cohort study. The main exposure variable was defined as the first psychiatric inpatient or outpatient contact for OCD. The outcome variable was defined as death by any natural cause (disease or medical condition) or unnatural cause (suicide, accident, or homicide) within the follow-up period. The cohort consisted of people born in Denmark between January 1, 1955, and November 31, 2006. The follow-up period started on the participants first birthday or January 1, 2002, whichever came later. The follow-up period ended on the date of emigration from Denmark, the date of death, or December 31, 2011, whichever came first. This information provided us with a maximum follow-up period of 10 years and a maximum age of 57 years for the cohort members. We focused on this 10-year period because during this period, the causes of death were grouped based on the same coding procedure. We particularly focused on young age groups, to avoid dilution of the findings by large mortality effects among older people. Data on cohort members were collected by
