Late Diagnosis of Autism Spectrum Disorder – Missed or Over-Diagnosed?

Background:  Currently, nearly 30% of children in Maccabi Healthcare Services are diagnosed with Autism Spectrum Disorder (ASD) after the age of six years. Although the high rate of late diagnosis could be due to sparse symptoms or lack of ASD awareness, many children with late diagnoses underwent initial evaluations at a Child Developmental Center (CDC) when they were younger.

Objectives: To characterize children who were evaluated at a young age in the Child Developmental Center, did not receive an ASD diagnosis, and were later diagnosed with ASD by a child neurologist or psychiatrist.    

Methods:  A search of the Maccabi Healthcare Services computer registry was conducted for children who were diagnosed with ASD between 2004 and 2010 after the age of 6 years. All records were checked by the authors to eliminate technical errors and to confirm the age of ASD diagnosis.  Data was collected for children who prior to age six were evaluated at Maccabi's CDC in four areas: developmental pediatrics, psychology, speech language pathology and occupational therapy.  Relevant information included the age of child during evaluations as well as developmental diagnoses made by the CDC team. Evaluation summaries were searched for evidence of communication problems (such as abnormal eye contact or abnormal social development) and the children were subsequently divided into four groups: Group 1 – no record of CDC evaluation; Group 2 – no evidence of communication problems in CDC evaluations; Group 3 – some CDC evaluations contained evidence of communication problems, while others did not; and Group 4 – all CDC evaluations contained evidence of communication problems. 

Results:  Children who met the research criteria (n=159) had a mean age of ASD diagnosis of 93.4 months (16.1 SD).  Group 1 contained 51 children. Of the remaining 108 children, Group 2 included 71 children that had 290 evaluations at a mean age of 44.8 months.  The three leading diagnoses were language deficits, global delay, and attention problems.  Group 3 included 32 children that had 188 evaluations at a mean age of 43.9 months.   In 126 evaluations no clues for communication problems was found.  Group 4 included 5 children that had 17 evaluations at a mean age of 46.3 months.  The leading diagnoses for groups 3 and 4 were language deficits, behavior problems, and global delay. Altogether, out of 495 total evaluations from children in groups 2, 3, and 4, only 79 evaluations  (16%) contained a mention of a communication problem.

Conclusions:  Two-thirds of the children diagnosed after six years of age were evaluated at an early stage by a multidisciplinary developmental team at the CDC but did not receive an ASD diagnosis.   In the majority of evaluations, clues of communication problems could not be found. The discrepancy between early and late diagnosis figures call into question the reliability of later diagnoses, which in contrast to CDC evaluations, are not made following comprehensive evaluations from a developmental team.