Failure points in the early autism identification pathway for children aged 0–5 years: Why screening is not diagnosis

Early autism identification in children aged 0-5 years is often discussed in terms of screening accuracy, yet consequential delay frequently occurs across the pathway from first concern to referral, diagnostic assessment, and support. This critical narrative review examines early autism identification as a pathway problem rather than as a single testing event. It synthesizes evidence on developmental surveillance, autism-specific screening, parental and clinician concern, referral conversion, diagnostic waiting, service capacity, inequity, family burden, and pre-diagnostic support. Screening tools can identify an elevated likelihood of autism and may accelerate diagnosis for some screen-positive children, but they cannot confirm diagnosis or safely exclude autism when concern persists, and they do not compensate for failures in follow-up, referral, assessment capacity, or support initiation. Recent evidence supports a cautious interpretation of universal autism screening because diagnostic stability, screening accuracy, and intervention benefit in screen-detected children remain uncertain. Comparative evidence on the Modified Checklist for Autism in Toddlers, Revised with Follow-Up suggests context-dependent performance, including variable sensitivity, low or inconsistent positive predictive value, and age-dependent accuracy. Multicultural surveillance and implementation studies indicate that adding tools without aligning workflow, language support, follow-up systems, and service capacity may not improve pathway performance. The review argues that early autism identification should be evaluated through linked quality measures: response to concern, repeated surveillance following negative or ambiguous screening, referral completion, time to diagnostic assessment, support initiation before diagnostic closure, and equity of access. The clinical priority is not a perfect screening instrument in isolation, but faster, more coherent, and more equitable local pathways that translate concern into timely action.