Objective: While the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) shows high sensitivity for detecting autism spectrum disorder (ASD) when present (i.e. true positives), scores on the ADOS-2 may be falsely elevated for individuals with cognitive impairments or psychological concerns other than ASD (i.e. false positives). This study examined whether demographic, psychological, cognitive, and/or adaptive factors predict ADOS-2 false positives and which psychiatric diagnoses most often result in false positives.
Method: Sensitivity, specificity, false positive, and false negative rates were calculated among 214 5- to 16-year-old patients who completed an ADOS-2 (module 3) as part of an ASD diagnostic evaluation. Additional analyses were conducted with the 101 patients who received clinically elevated ADOS-2 scores (i.e. 56 true positives and 45 false positives).
Results: Results revealed a 34% false positive rate and a 1% false negative rate. False positives were slightly more likely to be male, have lower restricted and repetitive behavior (RRB) severity scores on the ADOS-2, and demonstrate elevated anxiety during the ADOS-2. Neither IQ, adaptive functioning, nor caregiver-reported emotional functioning was predictive of false positive status. Trauma-related psychiatric diagnoses were more common among false positives.
Conclusions: The ADOS-2 should not be used in isolation to assess for ASD, and, in psychiatrically-complex cases, RRB symptom severity may be particularly helpful in differentiating ASD from other psychiatric conditions. Additionally, heightened levels of anxiety, more so than overactivity or disruptive behavior, may lead to non-ASD specific elevations in ADOS-2 scores.
Keywords: Autism spectrum disorder; assessment; diagnostic accuracy; differential diagnosis; false positives.