Prevalence Rates

How many people are affected by ASD?

In March 2018, the National Autism Spectrum Disorder Surveillance System (NASS) released the most up-to-date Canadian prevalence rate: 1 in 66 Canadian children and youth (ages 5-17) are diagnosed with Autism Spectrum Disorder (ASD), making ASD one of the most common developmental disabilities. According to the Canadian Medical Association Journal, approximately 1 - 2% of the Canadian population is affected by ASD, which means there are approximately 135,000 Ontarians on the autism spectrum.

These results impact Canadians living with ASD, as well as their families and caregivers. We can now say with confidence that the rates of ASD are increasing in Canada and so is the urgency to meet the needs of children, youth and adults on the autism spectrum, and their families.

Other key findings of the NASS report include that boys have received an ASD diagnosis four times more frequently than girls. More than half of children and youth with ASD were diagnosed by age six, and more than 90% received a diagnosis by age 12. Canadian prevalence estimates found in the report are similar to the most recent CDC rates.


How are prevalence rates calculated?

Prevalence rates are calculated by dividing the number of children identified with ASD who live in a specific area at any time during a given year by the total number of children who live in that specific area in that year. The ratio is an average, based on a period in time, surveying a specific area and a specific age group.

In Canada, surveillance varies from province to province. For this initiative, the NASS studied Canadian children diagnosed with ASD, ages 5-17, which is different from the current American prevalence rate of 1 in 59 children diagnosed with ASD, which only takes into account 8-year-old children from 11 surveillance regions.

It’s important to note that this data was collected in 2015. While Ontario isn’t reflected in the 2015 data, our province has been actively engaged with this project, which is good news for our families.


Why is the rate of Autism Spectrum Disorder growing?

While we don’t know why, we do know that the rate of ASD is increasing and it is placing huge demands on the education, healthcare and social service systems and highlighting glaring gaps in the supports available. Updated figures are important because prevalence rates and surveillance studies perform an important service for policymakers, system administrators and advocates.

Canadian research is not only vital to understanding the causes and effects of Autism Spectrum Disorder, but also to making sure that people and families living in Canada who are affected by ASD receive the best possible support. The NASS project reflects the most up-to-date epidemiological study to look at autism rates in Canada, and this is important to us as an Ontario/Canadian organization.


There are so many numbers. Which is the right one?

There is no “right” rate. There are a number of averages out there to describe a number of areas reporting ASD diagnoses. These numbers will change over time for a variety of reasons.

The way researchers collect data for prevalence rates is inconsistent. Tracking ASD isn’t done the same way across Canada, the United States, Europe, Africa, Central and South America, Asia, and Australia. This means that globally, there are different pictures of the rates of ASD diagnosis. A website based in the United States will give you one rate, where you might find a different rate on a website in Europe.

It’s easy to think about ASD as a number; however, we are not talking about a number. We are talking about a person. We are talking about a person with individual needs and loving family members. We are talking about a person who should be granted equal opportunity in preparing for and succeeding in adulthood. Rates like this help us to advocate for the individual needs of all people with ASD throughout their lifespan using evidence-based interventions while remembering that developmental trajectories are constantly changing. Our province must be prepared to support children, youth and adults within the context of development, learning, family, and community. This new rate will help to ensure that policymakers, system administrators, advocates, and self-advocates have current data to support their work in ensuring that each person with ASD is provided with the means to achieve quality of life as a respected member of society.