ICD-10 classification in Danish child and adolescent psychiatry--have diagnoses changed after the introduction of ICD-10?

The aim was to test this in a nationwide register study of diagnoses used in child and adolescents psychiatry in Denmark. A larger number of different diagnoses were expected to be applied after the introduction of the 10th version of the International Classification of Diseases (ICD-10). Reflecting the time trend, we particularly expected an increase in the number of neuropsychiatric diagnoses. From the Danish Psychiatric Central Register data were drawn on clinical discharge diagnoses. All patients aged 0-15 years examined at psychiatric hospitals from 1995-2002 were included; 22,469 children and adolescents with a first contact were registered. The most frequent discharge diagnoses were pervasive development disorders (PDD; 11.9%), adjustment disorders (10.6%), conduct disorder (9.5%), emotional and anxiety disorders (7.6%), hyperkinetic disorders (7.3%), and specific developmental disorders (7.3%). We found a significant increase in the number of neuropsychiatric and affective diagnoses and a significant decrease in the number of adjustment, conduct and anxiety diagnoses during the study period. Of the 22,469 diagnoses, 45% were only partly specified according to ICD-10. Thirty-four per cent had diagnoses unspecified on the four-character level (Fxx.9) and 11% had Z-diagnoses. A larger number of different diagnoses and an increase in the use of neuropsychiatric diagnoses were seen after the introduction of ICD-10. Many diagnoses were only partly specified; consequently, a more detailed specification of the ICD-10 is still required.