An epidemiological and diagnostic study of Asperger syndrome according to four sets of diagnostic criteria.

OBJECTIVE

This study evaluated the diagnostic process and prevalence rates of Asperger syndrome (AS) according to the DSM-IV, ICD-10, and criteria developed by Gillberg and Gillberg and by Szatmari and colleagues and clarified confusion about AS.

METHOD: An epidemiological study of 5,484 eight-year-old children in Finland, 4,422 (80.6%) of whom rated on the high-functioning Autism Spectrum Screening Questionnaire by parents and/or teacher, 125 of them screened and 110 examined by using structured interview, semistructured observation, IQ measurement, school day observation, and patient records. Diagnoses were performed by following the DSM-IV, ICD-10, and criteria developed by Gillberg and Gillberg and by Szatmari and colleagues in detail.

RESULTS

The prevalence rates per 1,000 were 2.5 according to the DSM-IV, 2.9 to ICD-10, 2.7 to Gillberg and Gillberg's criteria, and 1.6 to the criteria of Szatmari et al.

CONCLUSIONS

The results emphasize the need to reconsider the diagnostic criteria of AS. The importance of multi-informant sources came up, and the need of several informants was highlighted, especially when diagnosing the broader pervasive developmental disorders.