Identifying Childhood Psychiatric Disorders from Health Registries

We retrieved any records of diagnosed child or adolescent psychiatric disorder from the Danish health registries. All live-born children in Denmark are assigned a unique civil registration number that is linked to the National Patient Register.^{14 (link)} We obtained data on psychiatric disorders from both in-patient admissions and out-patient contacts. We were interested first in main diagnoses in any of the following diagnostic groups: any psychiatric disorder (ICD-10: F00-F99); schizophrenia, schizotypal and delusional disorders (ICD-10: F20 – F29); mood disorders, anxiety, dissociative, stress-related, somatoform and other nonpsychotic mental disorders (ICD-10: F30-F45, F48, F93); autism spectrum disorders (ICD-10: F84 not: F84.2-F84.4); personality disorders (F60-F69); hyperkinetic disorders (ICD-10: F90, F98.9); and conduct disorders (ICD-10: F91, F90.1).¹⁵ Thus, the disorder-specific diagnostic groups were not mutually exclusive. We formed a group of children and adolescents with, presumably, milder mental disorders^{16 (link)} who had redeemed two or more prescriptions of psychotropic drugs without being registered with a psychiatric diagnosis (ACT groups: N05, N06A, N06B, N06C).^{17 (link)}