Objectives: The Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) is a revision of the standardized assessment for individuals with suspected autism spectrum disorders (ASD). The study examines the diagnostic accuracy of the original and revised algorithms for Modules 1 through 3.
Methods: In a large clinical sample of children and adolescents (N = 1080, age 1.7 to 20.5), the differentiation of ASD from relevant differential diagnoses was investigated. As studies on the diagnostic accuracy for girls are sparse, comparisons concerning the diagnostic accuracy for gender subgroups were undertaken.
Results: The revised algorithms exhibit an improvement in sensitivity (84.9 %) and a slight reduction in specificity (85.7 %). The improvements in the ADOS-2 pertain especially to cases with core autism and girls. Including the repetitive behavior domain in the algorithm contributes to a correct clinical ASD classification in modules 2 and 3. This was not found for younger children examined with module 1. Results also suggest less effective diagnostic differentiation for children and adolescents with internalizing disorders and conduct disorder.
Conclusions: Good diagnostic accuracy was found for children in the average range of cognitive abilities. Results suggest good diagnostic utility for the ADOS-2 in clinical settings, provided that thorough diagnostics are given by experienced examiners.
Keywords: ADOS; diagnosis of autism spectrum disorder; sensitivity; specificity.