During the initial assessment, differentiate between autism spectrum disorder (ASD) and other developmental disorders by gathering detailed developmental history, focusing on features consistent with ICD-11 or DSM-5 criteria, including social and communication skills and behaviors, and observing the child's interaction in different settings NICE CG128.
Consider the impact on activities of daily living and the presence of restricted or repetitive behaviors specific to autism, while also evaluating for other neurodevelopmental, mental, behavioral, or medical conditions that may mimic or coexist with autism, such as language delay, intellectual disability, ADHD, or sensory impairments NICE CG128.
Use information from multiple sources, including parent/carer concerns, social and educational history, and clinical observations, to identify features unique to autism versus other developmental disorders NICE CG128.
If discrepancies arise between reported symptoms and observed behaviors, gather additional information from other settings or sources to clarify the diagnosis NICE CG128.