OBJECTIVE: This project focused on the development of the definition of
autism for DSM-IV. METHOD: Multiple sites were involved in obtaining
information regarding 977 patients with the following clinician- assigned
diagnoses: autism (N = 454), other pervasive developmental disorders (N =
240), and other disorders (N = 283). A standard coding system was used, and
the raters (N = 125) had a range of experience in the diagnosis of autism.
Patterns of agreement among existing diagnostic systems were examined, as
was the rationale for inclusion of other disorders within the class of
pervasive developmental disorders. RESULTS: The DSM-III-R definition of
autism was found to be overly broad. The proposed ICD-10 definition most
closely approximated the clinicians' diagnoses. Inclusion of other
disorders within pervasive developmental disorders appeared justified.
Partly on the basis of these data, modifications in the ICD-10 definition
were made; this and the DSM-IV definition are conceptually identical.
CONCLUSIONS: The resulting convergence of the DSM-IV and ICD-10 systems
should facilitate both research and clinical service.