Age at diagnosis of autism spectrum disorders in four regions of Canada

H.M.J. Ouellette-Kuntz, H. Coo, M. Larn, C.T. Yu, M.M. Breitenbach, P.E. Hennessey, J.J.A. Holden, H.K. Brown, A.L. Noonan, R.B. Gauthier, L.R. Crews


Objectives: Early diagnosis of autism spectrum disorders ("autism") may lead to better treatment outcomes, reduces the stress parents experience when they do not understand the reasons for their child's behaviour, and empowers parents to make choices such as seeking genetic counseling. We examined the age at which Canadian children are diagnosed with autism, and analyzed whether there are geographic or temporal variations or differences by sex or diagnostic subtype.

Methods: As part of an autism surveillance program, in 2002/2003 we began collecting information on children with autism in Manitoba, Southeastern Ontario, Prince Edward Island, and Newfoundland and Labrador. For the analysis presented in this paper, we included children identified for our surveillance program who were diagnosed between 1997 and 2005 (n=769).

Results: We found significant inter-regional differences in age at diagnosis, with Newfoundland and Labrador having the lowest median age at diagnosis (39.0 months) and Southeastern Ontario the highest (55.0 months). Diagnostic subtype was significantly associated with age at diagnosis in all regions. Southeastern Ontario was the only region where the overall age at diagnosis increased over time (p=0.004), although in Manitoba the age at which children were diagnosed with PDD-NOS also increased significantly over the study period (p=0.021).

Conclusions: Our findings demonstrate that there are geographic differences and other sources of variation in the age at which Canadian children are diagnosed with autism. Further study is warranted to understand the factors contributing to these differences. Such research would inform best practices for early detection and timely access to treatment.

Key words: Autism; autism spectrum disorders; early identification; age at diagnosis

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