A Scale to Assist the Diagnosis of Autism Spectrum Disorders in Adults: Results of An International Multi -Center Study

Background: An initial version of The Ritvo Autism Asperger Diagnostic Scale (RAADS) contained 78 questions. Published data demonstrated that it was valid, reliable, highly sensitive, and highly specific in a limited number of subjects. Questions assess developmental pathology in three symptom areas (language, social relatedness, sensory-motor responses per DSM-IV TR). The new 80-item version reported herein was developed after critical review led to the addition of two questions and wording clarifications. Objectives: To present initial findings of an international multi-center standardization study of the new 80-item version of the scale. Methods: Adult ASD subjects at eight university medical centers (three in Australia, four in the USA, one in Canada) were diagnosed by research criteria which included: 1) a clinical interview, 2) a Constantino SRS Scale, 3) an ADOS Scale to assess validity, 4) a standardized IQ test, 5) repeat testing to asses reliability. Comparison subjects were: 1) Volunteers without a DSM IV -TM diagnosis, 2) Volunteers who had a current DSM IV-TM diagnosis other than an autism spectrum disorder. Translations that take into account cultural variations, core syndrome regardless of language, and will permit standardization of results and assessment of validity and reliability are in early stages of development. They are being conducted at the Karolinska Institute, Stockholm, Sweden and at Nagoya, Japan. Results: The results to date demonstrate that the new 80 item version of the scale is highly valid and highly reliable (sensitivity and specificity >90%, test retest data show no significant change in scores over a one year interval) . Conclusions: The scale can assist clinicians diagnosing autism spectrum disorders in adults.