Better diagnosis leads to higher autism rates
A study by researchers at Perth's The Kids for Child Health Research has found that the rapid increase in the number of children diagnosed with autism spectrum disorders (ASD) in Western Australia reflects changes to diagnostic practices and services.
The research will be published in this month's edition of the International Journal of Epidemiology.
Research co-author Dr Emma Glasson said the study investigated factors behind the concerning increase in autism rates.
"We wanted to address community concerns as to why there are so many more young children being diagnosed in recent years with autism spectrum disorders," Dr Glasson said.
"While a true increase can't be ruled out, there is a very definite pattern that shows the increase coincides with changes to the way autism was diagnosed and the provision of funding for early intervention services."
The study found that in 1983 1.7 in every 10 000 children born in WA were diagnosed with ASD by age 8 compared with 53.4 per 10 000 children born in 1997, representing a 16.6% increase per annum.
From the late 1980s there was a parent-initiated drive towards more proactive early intervention services. In 1991 a new panel was set up to determine the eligibility of children for services. In 1994 the diagnosis of Asperger syndrome was introduced. In 1997 new funding was made available for early intervention for pre-school children.
Dr Glasson said the study also observed that children were being diagnosed at a younger age, reflecting better awareness and parents' willingness to access early intervention services.
"Early diagnosis and specialised services will give children with autism spectrum disorders and their families the best results," Dr Glasson said.
"While we need to do more research to see if there is also a real increase in prevalence, we are confident that a substantial proportion of this rapid rise is due to better diagnosis and access to services."
The research was supported by funding through the National Health and Medical Research Council.
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Citation: Natasha Nassar, Glenys Dixon, Jenny Bourke, Carol Bower, Emma Glasson, Nick de Klerk and Helen Leonard "Autism spectrum disorders in young children: effect of changes in diagnostic practices" International Journal of Epidemiology 2009; 1-10