Sensitivity and Specificity of Common Autism Diagnostic Instruments for Early School-Aged Children

Background/Objectives: This study assessed the diagnostic accuracy of two commonly used diagnostic instruments for autism spectrum disorder (ASD), the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) and the Autism Diagnostic Interview-Revised (ADI-R), in comparison to a best-estimate (BE) diagnosis made by a research psychologist. Methods: Two hundred and thirteen children aged 5 years 0 months to 7 years 11 months completed a comprehensive research assessment that included multiple diagnostic measures. Once each research assessment was complete, a research psychologist gave each participant an overall BE research diagnosis of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) ASD based on all available information from diagnostic testing and behavioral observations during testing. We assessed sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of both the ADOS-2 and ADI-R separately and in combination and used receiver operating characteristic (ROC) curves to compare the areas under the curve (AUCs) of these instruments. Results: Both the ADOS-2 Spectrum Criterion scoring (sensitivity = 96.2%; specificity = 97.5%) and ADOS-2 Autism Criterion scoring (sensitivity = 82.0%; specificity = 100%) had excellent accuracy in comparison to the BE ASD diagnosis. The ADI-R had good accuracy (sensitivity = 78.6%; specificity = 83.5%) compared to BE ASD diagnosis. In receiver operating curve analyses, both scoring criteria for ADOS-2 were significantly more accurate than the ADI-R. Conclusions: Overall, both instruments provide good, if not excellent, classification accuracies when used individually, as well as in combination. Thus, when deciding which measures to use for ASD research, other factors should also be considered.