Expressive Language Sample Concordance With ADOS-2 Scores: Autism, Down Syndrome, Fragile X Syndrome.

Mazurek et al. (2019) put forth an Expressive Language (EL) score based on the Autism Diagnostic Observation Schedule, Second Edition Module administered and Item A1, establishing convergent validity with expressive language assessments for autism. The current study examines EL score relationships with transcribed language samples-including sensitivity to change-across 6- to 23-year-old individuals in three diagnostic groups: autism, Down syndrome, and Fragile X syndrome. Results demonstrate convergent validity of EL score with language complexity and lexical diversity, and variable patterns of divergence with talkativeness and nonverbal participation. In contrast to mean length of utterance in morphemes, EL score was not sensitive to 1-year change. These findings support the usefulness of EL score for quickly describing expressive language, but caution against its use as a clinical outcome or measure of change.