Diagnostic assessment of Asperger's disorder: a review of five third-party rating scales.

Five rating scales for screening and detection of Asperger's Disorder, three commercially available and two research instruments, are evaluated with reference to psychometric criteria outlined by Bracken in 1987 (Journal of Psychoeducational Assessment, 4, 313). Reliability and validity data reported in examiner's manuals or published reports are reviewed. The scales included in the review are the Asperger Syndrome Diagnostic Scale (ASDS), Autism Spectrum Screening Questionnaire (ASSQ), Childhood Asperger Syndrome Test (CAST), Gilliam Asperger's Disorder Scale (GADS), and Krug Asperger's Disorder Index (KADI). All published rating scales demonstrated significant weaknesses, particularly in the use of questionable normative samples. Among the published instruments, the KADI appears to be the most sound in terms of reliability and validity. The research instruments present incomplete psychometric data to date, but hold promise as clinical instruments.