The TRAILS database was linked to files of the Preventive Child Healthcare services to obtain information on pre- and perinatal factors such as maternal smoking during pregnancy, birthweight and early childhood behavioural features.17 In addition, the database was recently linked to the Psychiatric Case Registry North Netherlands (PCRNN), which registers mental healthcare use since 2000. The register includes specialist treatment in child, adolescent and adult mental health, and substance abuse service organizations. The PCRNN registers the number of ‘care events’, subdivided into outpatient contacts, part-time treatment days and clinical care days (24 h). We aim to realize a linkage to general practitioner information systems within 3 years.
