Emily Acraman
We are often asked “what percentage of the New Zealand population are autistic” and “how common is an autism diagnosis” … our researcher Emily Acraman answers this question here.
16 August 2021 – There is no definitive information on the national prevalence and incidence of autism, as New Zealand does not record this type of data.
Rather, New Zealand statistics are based on data reported in other countries and generalised to our population. Based on international data, it is estimated between 1-2% of people in New Zealand are autistic. That’s between 50,000 to 100,000 people.
International Research
One of the leading sources of autism prevalence data is published in the United States by the Centers for Disease Control and Prevention (CDC).
This biannual report estimates the prevalence of autism among children (8 years old), based on national surveillance monitoring data.
The latest update of this report (2020) estimates that in children 8 years of age, approximately 18.5 per 1,000 (one in 54 children) are diagnosed as autistic. This figure is roughly 10% higher than the prevalence estimates from the previous report (published in 2018) which were 16.8 per 1,000 (one in 59 people). And approximately 175% higher than the estimates reported by the CDC network in their first report (published in 2007), which reported the prevalence of autism to be 6.7 per 1,000 children (Maenner et al, 2020).
The report also demonstrates that autism is 4.3 times more common (or more diagnosed) in boys than in girls. As well, autism occurs in all racial, ethnic and socioeconomic groups. Previous reports estimated autism was approximately 20%-30% higher among white children compared with black children, however the latest report notes this difference has dropped to 7%.
Canda have also recently released their first national surveillance report which monitors the rates of autism among 5 to 17-year-olds across Canada. In 2018, the first National Autism Surveillance System (NASS) report was published which estimated the prevalence of autism among 5 to 17-year-olds was 15.2 per 1,000 (1 in 66 children). Slightly lower than those reported by the US CDC in 2018 (1 in 59 children). The report also showed autistic males were diagnosed four times more frequently than females (Ofner et al., 2018).
New Zealand Research
New Zealand studies examining the incidence of autism in our population have been conducted, however on a much smaller scale. Thus, generally the New Zealand studies in this area tend to underestimate autism prevalence.
Early last year a New Zealand study was published which looked at the number of new autism diagnoses made between 2012-2016 in children aged between 0-19 years by the Hutt Valley District Health Board. This study demonstrated autism diagnoses were made in 1.48 per 1,000 children, and males were diagnosed 4 times more frequently than females. Of the 228 autistic young people that made up the study, 55.2% identified as New Zealand European, followed by 23.6% Māori, and 4.3% as Pasifika (Drysdale & van der Meer, 2020).
A second New Zealand study also published last year utilised three administrative health data sources to identify the number of children and young people diagnosed on the autism spectrum during 2015/2016. The study showed that in children 8-years-old, autism occurred in 1 out of every 102 children. As supported by all the above research, the study also found that autism was more common in males than females (approximately 3.6 to 1).
As well, that autism was slightly more common in New Zealand European ethnicity as opposed to Māori and Pasifika populations (Bowden et al, 2020).
Both these New Zealand studies report significantly lower rates of autistic people among the population in comparison to international research. It is likely these studies and the methods used to gather data undercount the occurrence of autism in New Zealand potentially by about 40% (Bowden et al, 2020). These studies do however aid in establishing a more comprehensive evidence base to inform research, policy and management and supports related to autism in New Zealand. As well, they provide a good estimate of the relative rates of autism among gender and ethnic groups in New Zealand.
Summary
Overall, it is difficult to say exactly how much of our population in New Zealand are autistic, because this data is not currently gathered. From international data, we can estimate approximately 1%-2% of our population are autistic, or approximately 1 in 54 young people. International research suggests the prevalence of autism is on the rise, however it is still difficult to say whether autism is becoming more common, or that it is just being more frequently diagnosed. Improvements in understanding and identification as well as broader diagnostic terms have likely contributed to this increase (Bowden et al, 2020). Our consultant clinical psychologist Jenny Gibbs draws on this more in her article .
New Zealand attempts at investigating autism prevalence in New Zealand, have limitations, and likely underreport the true rates of autism in our population. However, these studies do provide significant steps towards establishing a more comprehensive evidence base to inform autism policy and practices in New Zealand (Bowden et al, 2020).
References
Bowden, N., Thabrew, H., Kokaua, J., et al. (2020). Autism spectrum disorder/Takiwātanga: An integrated data infrastructure-based approach to autism spectrum disorder research in New Zealand. Autism, 24(8). https://doi.org/10.1177/1362361320939329
Drysdale, H., & van der Meer, L. (2020). Rates of autism spectrum disorder diagnosis for children and adolescents in the Hutt Valley region of New Zealand between 2012 and 2016. Research in Autism Spectrum Disorders, 73(ss-6). https://doi.org/10.1016/j.rasd.2020.101547
Maenner, M. J., Shaw, K.A., Baio, J., et al. (2020). Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2016. MMWR Surveill Summ, 69(4), 1-12. Read here.
Ofner, M., Coles, A., Decou, M. L., et al. (2018). Autism spectrum disorder among children and youth in Canada 2018: A report of the National Autism Spectrum Disorder Surveillance System. Ottawa, Canada: Public Health Agency of Canada. Retrieved from: https://www.canada.ca/en/public-health/services/publications/diseases-conditions/autism-spectrum-disorder-children-youth-canada-2018.html