Factors associated with the age of diagnosis of autism in Australia: barriers and enablers to early identification policy responses

Submission note: A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Olga Tennison Autism Research Centre, School of Psychology and Public Health, College of Science, Health & Engineering, La Trobe University, Bundoora, Victoria.

Thesis with publications.

This thesis presents findings from four related research studies, which aim to identify child, family, service, and community level factors that are enablers and barriers to the early identification of autism in Australia. De-identified data was obtained from the Australian Government Department of Social Services regarding children registered with the Helping Children with Autism Package (HCWA) between 2010 and 2015. An online survey was also conducted with 185 parents of children with autism. The average age of diagnosis (AOD) of children with autism in Australia was approximately 4 years of age, highlighting that there is a substantial gap between the age that research suggests a reliable diagnosis is possible (~ 2 years) and the AOD of autism in the community. Children of culturally and linguistically diverse or Indigenous origin were less likely to receive an Asperger’s Disorder diagnosis by age 7, suggesting that children from cultural minority groups who present with milder symptoms may be at risk of delayed diagnosis. Family characteristics associated with earlier diagnoses included earlier parent concerns, while higher caregiver education was associated with a shorter delay between parents first raising concerns and obtaining a diagnosis. Service characteristics identified as potential barriers included increased demand for diagnostic services, as slight increases in AOD corresponded to increases in the frequency of diagnoses over time. More proactive professional responses to parents’ concerns, and consulting fewer health professionals were associated with earlier diagnoses. No change in AOD, or direct reduction in the number of children accessing HCWA was observed following the introduction of the revised autism diagnostic criteria in 2013. However, findings suggest the increasing incidence of autism diagnoses may have plateaud. Differences were evident in AOD across states and communities, and community indicators of socio-economic status and population diversity were associated with these differences. In Victoria, a meaningful (but not statistically significant) relationship was evident between the average AOD of autism in a community and the proportion of children attending Maternal and Child Health consultations at 12-, 18-, and 24 months. The study findings have implications for the development and targeting of public health initiates that promote earlier diagnoses and access to services. Highlighting the need to streamline current pathways to care, and for continued capacity building to support diagnostic services to deliver timely and accurate assessments to families.

This thesis was a recipient of the Nancy Millis Award for theses of exceptional merit.