No abstract

In 2002/2003, the National Epidemiologic Database for the Study of Autism in Canada started capturing information on children diagnosed with autism in different regions of the country. Based on data collected through 2008 in Newfoundland and Labrador and 2010 in Prince Edward Island and Southeastern Ontario, the estimated average annual percent increases in prevalence among children 2-14 years of age ranged from 9.7 % (95 % CI 7.8-11.6) to 14.6 % (95 % CI 11.3-18.0). Differential in-migration and identification of previously undetected cases may have contributed in part to the increases observed, but we cannot rule out the possibility of a true increase in incidence, particularly given the lack of a leveling-off of prevalence among the 6- to 9-year olds.

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.

Introduction Early identification of autism spectrum disorders (ASD) is important, since earlier exposure to behavioural intervention programs may result in better outcomes for the child. Moreover, it allows families timely access to other treatments and supports. Methods Using generalized linear modeling, we examined the association between child and family characteristics and the age at which 2180 children were diagnosed with ASD between 1997 and 2005 in six Canadian regions. Results A diagnosis of pervasive developmental disorder-not otherwise specified (PDD-NOS) or Asperger syndrome, rural residence, diagnosis in more recent years, and foreign birthplace were associated with a later age at diagnosis. Children who are visible minorities or who have siblings with ASD were more likely to be diagnosed earlier. Collectively, these factors explained little of the variation in age at diagnosis, however. Conclusion While it is encouraging that ethnocultural identity, neighbourhood income, urban or rural residence, and sex of the child were not major contributors to disparities in the age when children were identified with ASD, more work is needed to determine what does account for the differences observed. Regional variations in the impact of several factors suggest that aggregating data may not be an optimal strategy if the findings are meant to inform policy and clinical practice at the local level.

‡ ‡ Date of birth, sex, prevalence year (year in which the child was first known to have an ASD diagnosis and reside in the surveillance region), diagnostic subgroup.