Examination of the Time Between First Evaluation and First Autism Spectrum Diagnosis in a Population-based Sample

TLDR

Early identification of young children with autism spectrum disorder can lead to earlier intervention and improved developmental outcomes. This study examined identification and diagnostic patterns of children with ASD in a large metropolitan area. The authors analyzed 115 eight‑year‑old children identified through CDC surveillance, focusing on earliest evaluation and diagnosis ages, initial diagnosis type, evaluation source, professional characteristics, and diagnostic tools used. Children were first evaluated at an average of 48 months and diagnosed at 61 months, with no sex or racial differences but impairment severity predicting timing; most were identified outside schools, 24 % received a diagnosis only upon school entry, and 70 % of practitioners did not use a diagnostic instrument.

Abstract

Early identification of young children with an autism spectrum disorder (ASD) can lead to earlier entry into intervention programs that support improved developmental outcomes. The purpose of the present study was to examine identification and diagnostic patterns of children with ASD who live in a large metropolitan area. One hundred fifteen 8-year-old children diagnosed with ASD were identified from a population-based surveillance system at the Centers for Disease Control and Prevention. Primary variables of interest included earliest age of evaluation and earliest age of diagnosis identified from surveillance records, type of initial ASD diagnosis, evaluation sources that documented first ASD diagnosis, characteristics of professionals assigning first ASD diagnosis, and diagnostic tools used to aid the diagnostic process. We found that children with ASD identified by the surveillance system were initially evaluated at a mean of 48 months but were not diagnosed with ASD until a mean age of 61 months. There were no differences in timing of diagnosis based on sex or racial/ethnic classification, although degree of impairment associated with ASD predicted mean age at first evaluation and mean age at first ASD diagnosis. Most children were identified at nonschool sources, such as hospitals and clinics; 24% of the sample did not receive a documented ASD diagnosis until entering school. Most practitioners (70%) did not use a diagnostic instrument when assigning the first ASD diagnosis. Implications for early identification of ASD are discussed.