Study Design

We followed the cohort from their 10th birthday or January 1, 1995, whichever occurred last, until the date of their first diagnosis of interest, death, emigration from Denmark, disappearance or January 1, 2014, whichever occurred first. By following individuals from age 10 we exclusively included persons at risk of the psychiatric diagnosis of interest, ie, persons with a history of the disorder before their 10th birthday were excluded. The year 1985 was chosen as the cut-off limit to ensure incident cases of traumatic stress disorder (introduced in the ICD-10), and to include outpatient diagnoses which were included from 1995.