The Autism Diagnostic Observation Schedule is a semi-structured, standardized assessment tool for individuals with suspected autism spectrum disorders (ASD) and is deemed to be part of the gold standard for diagnostic evaluation. Good diagnostic accuracy and interpersonal objectivity have been demonstrated for the ADOS in research setting. The question arises whether this is also true for daily clinical practice and whether diagnostic accuracy depends on specialized experience in the diagnostic evaluation. The present study explores the diagnostic accuracy of the original and the revised version of the ADOS for Modules 1 through 4. Thus, seven cases of ADOS executions were recorded and coded by a group of experts of specialized outpatient clinics for ASD. In an extensive consensus process, including video analysis of every minute of the ADOS executions, a "gold standard" coding for every case was defined. The videos of the ADOS administration were presented to a large group of clinicians (from daily clinical routine care) and their codings (n = 189) were obtained and analysed. Variance of coding and congruence with the expert coding were determined. High variance was found in the codings. The accuracy of the coding depends on the experience of the coder with the ADOS as well as on characteristics of the cases and the quality of the administration of the ADOS. Specialization in the diagnostic of ASD has to be claimed. Specialized outpatient clinics for ASD are required which guarantee a qualified diagnostic/differential diagnostic and case management with the aim of demand-oriented supply of individual cases.
Keywords: Autism spectrum disorder; Diagnosis; Diagnostic accuracy; Inter-rater agreement.