Prevalence and Comorbidities of Autism Spectrum Disorder and Study of the Method of the Developmental Health Checkup in a Japanese Community-Based Population Sample of Five-Year-Old Children

Background: In Japan, local governments perform pregnant women and infants’ health check-up as a fundamental maternal-and-child-health service. However, it cannot completely pick up developmental disabilities, especially ASD at 18 months and 36 months old. Therefore, we have conducted five-year-olds developmental health check-up since 2013, and directly diagnosed developmental disorders using DSM-5. It allows investigating the prevalence of developmental disorders, and proposing early identification and intervention.

Objectives: The purpose of this study is to investigate the prevalence and Comorbidities of ASD in a community-based population sample of five-year-old children. We also clarify the difference of clinical data between children with ASD or other developmental disorders and healthy controls.

Methods: This study was conducted as Hirosaki Five years check-up (HFC) study-assessing mental health among children in Hirosaki. Subjects are 3804 children who become 5 years old between April 2013 and March 2016 in Hirosaki city. 2923 children responded to the first screening (parents and teacher filled out ASSQ, SDQ, ADHD-RS, DCDQ, PSI-C). 607 children were above the cutoff point of the screenings. Finally, 440 children and their parents visited to the developmental health check-up including 31 applicants. Pediatricians and psychiatrists diagnosed neurodevelopmental disorder directly using DSM-5 criteria (ASD, ADHD, ID/BI) and EACD criteria (DCD), in addition, psychologists and Occupational therapists evaluated not only ASD symptoms but also cognitive and motor function using WISC-4, MABC-2, SCQ, AQ, PARS-TR short version. We estimated the rate of prevalence and comorbidities. In addition, we verified the availability of the screening and assessment tools.

Results: The prevalence rate of ASD was estimated at 3.20%. The comorbidities of ASD were ADHD (60.0%), DCD (61.1%) and ID/BI (40.0%). In the logistic regression analysis, the primary screenings which are combination of parent-ASSQ, ADHD-RS, PSI-C and teacher’s SDQ showed 96.9% prediction diagnostic rate (R²=.559). Similarly, the secondary assessment tools which are combination of MABC Total, AQ Total and PARS-TR short-version showed 86.2% prediction diagnostic rate (R²=.479).

Conclusions: This is the first epidemiological study of a community-based population sample in Japan. These findings suggest that ASD children have plural comorbidities, in other words, ASD children suffer from severe disabilities than other disorders. ASSQ, ADHD-RS, PSI-C, SDQ is useful for screening and MABC-2, AQ, PARS-TR is available for diagnosis of 5-year-old ASD children.