Classification, as a means of ordering information and grouping phenomena, is basic to all forms of scientific enquiry. There is a basic difference between classification and diagnosis of child psychiatric disorders. Untill 1969 no acceptable classification system was available.
The tri-axial approach to classification, as recommanded by the Third WHO seminar on standarisation of psychiatric diagnosis, classification and statistics, have been put into daily clinical practice at the University of Utrecht Child Psychiatric Department.
The first axis of the scheme concerns the clinical psychiatric syndrome, the second axis describes the child's level of intellectual functioning and the third axis notes any associated or aetiological factors.
Experiences and problems encountered in practising this classification system are illustrated by clinical vignettes.
The results of classification of 1287 patients between 0 and 16 years of age are reported. Statistical analysis of the results shows a striking conformity during the years. This is considered as the results of a fairly high interjudgereliability and a certain degree of overlap between categories.
The tri-axial classification approach has proved to be useful and preferable. However further research is needed to validate the categories included.