Prevalence of profound autism (per updated 2025 and prior 2021 definitions) and availability of required assessment data (IQ, verbal status, adaptive functioning) among 7,084 8-year-old children with autism across 13 US surveillance sites in 2022.
Using the updated 2025 definition (IQ <50 OR nonverbal/minimally verbal, AND adaptive functioning ≤70), profound autism prevalence was 5.4 per 1,000 8-year-olds (95% CI: 5.1–5.8), representing 16.5% of children with autism; nonprofound autism prevalence was 27.5 per 1,000. Critically, the full data needed to classify profound autism status was available for only 54.4% of children, with adaptive data missing in ~44% of cases.
Nearly half of children lacked complete assessment data, requiring imputation that may introduce classification error. The study is cross-sectional and surveillance-based, so it cannot capture longitudinal changes in profound autism status. Findings reflect 8-year-olds only and may not generalize to other age groups.
Clinicians should routinely collect IQ, verbal status, and adaptive functioning data when evaluating children with autism — currently, adaptive assessments are missing in nearly half of cases, making it impossible to accurately classify profound autism and direct appropriate services. The choice of definition matters greatly: using the prior 2021 definition inflates prevalence by 33.5%, highlighting the need for consistent adoption of the updated 2025 criteria.
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