ADOS-2 Toddler and Module 1 standardized severity scores as used by community practitioners

Abstract

BackgroundThe Autism Diagnostic Observation Schedule, 2nd edition (ADOS-2) is a diagnostic instrument which forms part of the recommended “gold standard” for the assessment of Autism Spectrum Disorder (ASD), however raw scores are affected by age, development and language level. Standardized calibrated severity scores (CSS), unlike raw scores, provide a relative metric of the severity of autism-specific symptoms. A CSS has recently been developed for the ADOS-2 Toddler Module, which can be used in children aged 12–30 months. The utility of this new algorithm has yet to be examined in an independent sample, and few studies have examined the ADOS-2 as used by community practitioners, rather than in a research environment. MethodTotal and domain standardized CSS for the ADOS-2 Toddler Module and Module 1 were examined in an independent, community based sample of 125 young children aged 20–47 months with a diagnosis of ASD, and in a comparison sample of children with nonspectrum diagnoses. ResultsThe CSS was more uniformly distributed when compared to raw scores across age and language groups, and less influenced by participant characteristics, including verbal DQ. Younger non-verbal participants returned higher CSS, suggestive of overlap with developmental and language level. Increased CSS in younger, nonverbal children may also reflect greater severity, thereby leading to earlier referral. The Child Behavior Checklist externalizing score emerged as an independent predictor of ASD symptom severity. ConclusionsThese results offer tentative support for the introduction of the Toddler Module CSS into community practice; however caution in the interpretation of the score in younger, nonverbal children is urged.