Describe a cohort of children who received a diagnosis of autism spectrum disorder (ASD) after age 6 and after having undergone a comprehensive multidisciplinary assessment before the age of 6, through which they were not diagnosed with ASD.
Extensive chart review of patients' electronic medical records comprised a representative population-based registry of patients seen during 2004 to 2011. The study focused only on the cohort of children who were diagnosed with ASD after the age of 6 but were not diagnosed with ASD at an earlier age. The charts were reviewed for the number of developmental assessments completed and the clinician's diagnostic impressions. The charts were also examined for documentation of ASD-suggestive features pulled directly from the text of the evaluators' reports.
A total of 221 patients (189 males) were diagnosed with ASD after age 6 although their initial comprehensive developmental evaluations before the age of 6 were negative for ASD. The study cohort underwent a total of 1028 developmental evaluations before the age of 6, with initial diagnostic impressions that included language deficits (70%), motor difficulties (67%), attention problems (46%), and cognitive difficulties (42%). Less than half of the cohort had ASD-suggesting features documented in their initial assessment.
Subsequent late diagnosis of ASD after an initial ASD-negative comprehensive assessment is a common clinical experience. Reasons for this scenario may include evolving diagnosis as well as missed and overdiagnosed cases of ASD.