Phenomenal and operationalized classification of psychiatric disorders in children and adolescents with ICD-9 and ICD-10, on the basis of a field study.

In connection with the implementation of ICD-10, a further multicenter field study was conducted with 33 raters from 9 facilities for child and adolescent psychiatry. Each rater evaluated the same 29 case studies, resulting in a total of 957 ratings. When coding was done with 4-character ICD-10 codes interrater agreement on a given diagnosis averaged 50.3% (ICD-9: 47.3%); with 3-character ICD-10 codes the figure was 61.0% (ICD-9: 66.5%). When alternative diagnoses were also considered, agreement improved by about 7% (4-character codes) and 7.4% (3-digit codes), respectively. The highest levels of agreement were found for monosymptomatic disorders (F94, F95 and F98), the lowest for mixed disorders of conduct and emotions (F92) and depressive disorders (F31, F43). These results indicate that, on the whole, psychiatric disorders in children and adolescents can be classified reliably with the ICD-10, even when the raters have had no experience with the scheme.