Autism spectrum disorder: Presentation and prevalence in a nationally representative Australian sample.
OBJECTIVE
The aim of this study was to identify the prevalence of parent-reported autism spectrum disorder diagnosis in Australia, and examine the developmental profile of children with autism spectrum disorder compared to their peers.


METHODS
Secondary analyses were undertaken on data from the Longitudinal Study of Australian Children.


METHODS
Children were recruited at kindergarten (K cohort) and birth (B cohort), and subsequently completed two-yearly 'waves' of assessments.


RESULTS
Autism spectrum disorder diagnostic status was ascertained at Wave 4 along with age of diagnosis by parent report. Standardised tools were used to assess children's quality of life, behaviour, receptive vocabulary and non-verbal intelligence.


RESULTS
Prevalence of autism spectrum disorder was 2.5% (95% confidence interval = [2.0, 3.0]) in the B cohort compared to 1.5% (95% confidence interval = [1.2, 2.0]) in the K cohort. In both cohorts, children with autism spectrum disorder had poorer mean quality of life, emotional-behavioural functioning and receptive vocabulary compared with non-autism spectrum disorder peers, and a higher proportion of children with autism spectrum disorder had problems in these areas. However, between 6% and 9% of children with moderate to severe autism spectrum disorder and 12-20% with mild autism spectrum disorder were not reported to have problems with social interaction.


CONCLUSIONS
The prevalence of a parent-reported diagnosis of autism spectrum disorder before age 7 in Australia was higher in the B cohort. Data from future Longitudinal Study of Australian Children waves will clarify whether autism spectrum disorder has been diagnosed earlier in the B cohort or if there is a continued increase in prevalence. Future waves will also provide crucial information about the types and severity of problems experienced during the primary and secondary school years which will assist service planning.
Australian Catholic University, Australia The Royal Children's Hospital, Australia.
Melinda
M
Randall
Murdoch Childrens Research Institute, Australia.
Emma
E
Sciberras
The University of Melbourne, Australia.
Amanda
A
Brignell
La Trobe University, Australia.
Elfriede
E
Ihsen
The Royal Children's Hospital, Australia Murdoch Childrens Research Institute, Australia.
Daryl
D
Efron
La Trobe University, Australia.
Cheryl
C
Dissanayake
Murdoch Childrens Research Institute, Australia The University of Melbourne, Australia La Trobe University, Australia katrina.williams@rch.org.au.
Katrina
K
Williams
D001315:Australia / Q000453:epidemiology; D000067877:Autism Spectrum Disorder / Q000453:epidemiology*; D002648:Child; D005260:Female; D006801:Humans; D007360:Intelligence; D007398:Interpersonal Relations; D008137:Longitudinal Studies; D008297:Male; D015995:Prevalence; D011569:Psychiatric Status Rating Scales; D011788:Quality of Life; D012720:Severity of Illness Index
Autism; epidemiology; prevalence