# Long-Term Outcomes of Early Autism Spectrum Disorder Screening: Prevalence and Diagnostic Stability in a Decade-Long Cohort from Türkiye

## TL;DR

This study tracks children in Türkiye over ten years to understand early autism screening outcomes and diagnostic stability.

## Contribution

The study provides a decade-long longitudinal analysis of early ASD screening and diagnostic stability in Türkiye.

## Key findings

- 1.4% of 1981 children screened were identified as at risk for ASD.
- 0.45% of children received an ASD diagnosis after initial evaluation.
- 11 children were diagnosed with ASD by the tenth year, with two diagnoses emerging later.

## Abstract

Objective: This study aimed to provide a reliable estimate of early childhood autism spectrum disorder (ASD) prevalence in Türkiye and to examine diagnostic stability and developmental trajectories through a ten-year longitudinal follow-up incorporating systematic early screening, structured parent-child observations, and repeated diagnostic assessments. Methods: A total of 1981 children aged 18-48 months were screened using the M-CHAT-R/F. Children who screened positive underwent an initial clinical assessment, including a family interview and structured parent-child observation. Those identified as at risk were referred for DSM-5-TR-based diagnostic evaluation by expert clinicians. Children diagnosed with ASD or classified as at risk were enrolled in a structured ten-year follow-up program. Results: Of the 1981 screened children, 27 (1.4%) were identified as at risk. Nine children (33.3% of at-risk; 0.45% of the total sample) received an ASD diagnosis following comprehensive evaluation. All retained their diagnosis during the 18-month follow-up. By the tenth year, two additional children from the at-risk group were diagnosed, bringing the total number of ASD cases to 11. Conclusions: These findings demonstrate that structured, multi-stage screening and diagnostic procedures are feasible and effective for early ASD identification in Türkiye. High diagnostic stability supports the reliability of early clinician-led assessments, while later-emerging cases highlight the importance of long-term monitoring of at-risk children.