Assessing Language Skills in Children Aged 4 to 6 Years with Autism Spectrum Disorder: A Prospective Study

<b>Background/Objectives:</b> Language impairments are highly prevalent in children with Autism Spectrum Disorder (ASD). In preschoolers (3-6 years), language development predicts future social outcomes. Despite the availability of standardized tests for typically developing children, few studies have specifically examined language impairments in preschool-aged children with ASD using these tools. This study aimed to comprehensively assess receptive and expressive lexicon, receptive comprehension, phonology and articulation using standardized tools, and to evaluate their feasibility. A secondary goal was to compare the results obtained with standardized tests to those from developmental batteries and hetero-assessments (caregiver reports). <b>Methods:</b> Forty-seven children with ASD aged 4 to 6 years participated. Assessments included standardized language tests, developmental batteries and hetero-assessments. The dichotomous Rasch model evaluated feasibility and item performance of standardized tests. Concordance across methods was analyzed via Pearson correlations and stepwise linear regression. <b>Results:</b> Standardized assessments were feasible for most participants despite wide variability in language abilities. Partial but non-equivalent concordance was found among assessment methods, each providing complementary insights into language profiles. <b>Conclusions:</b> Combining multiple assessment methods is crucial to capture the complexity of language development in children with ASD. Standardized tests can be adapted and provide more precise profiles than developmental batteries or hetero-assessments alone. A multimodal approach is essential to accurately identify language strengths and therapeutic targets in preschool-aged children with ASD.