Aim: To ascertain the incidence of autism spectrum disorders in Australian children.
Setting: New South Wales (NSW) and Western Australia (WA), July 1999 to December 2000.
Design: Data were obtained for WA from a prospective register and for NSW by active surveillance.
Main outcome measures: Newly recognised cases of autism spectrum disorders (defined as autistic disorder, Asperger disorder and pervasive developmental disorder not otherwise specified [PDD-NOS]) in children aged 0–14 years; incidence was estimated in 5-year age bands (0–4 years, 5–9 years, 10–14 years).
Results: In WA, 252 children aged 0–14 years were identified with autism spectrum disorder (169 with autistic disorder and 83 with Asperger disorder or PDD-NOS). Comparable figures in NSW were 532, 400 and 132, respectively. Most children were recognised with autistic disorder before school age (median age, 4 years in WA and 3 years in NSW). Incidence of autistic disorder in the 0–4-years age group was 5.5 per 10 000 in WA (95% CI, 4.5–6.7) and 4.3 per 10 000 in NSW (95% CI, 3.8–4.8). Incidence was lower in older age groups. The ratio of all autism spectrum disorders to autistic disorder alone was 1.5:1 in WA and 1.3:1 in NSW, and rose with age (1.8:1 and 2.9:1 in 10–14-year-olds in WA and NSW, respectively).
Conclusions: These are the first reported incidence rates for autism for a large Australian population and are similar to rates reported from the United Kingdom. Ongoing information gathering in WA and repeat active surveillance in NSW will help to monitor any future changes.
- 1. Fombonne E. Epidemiological surveys of autism and other pervasive developmental disorders: an update. J Autism Dev Disord 2003; 33: 365-382.
- 2. Wing L, Potter D. The epidemiology of autistic spectrum disorders: is the prevalence rising? Ment Retard Dev Disabil Res Rev 2002; 8: 151-161.
- 3. Prior M. Is there an increase in the prevalence of autism spectrum disorders? J Paediatr Child Health 2003; 39: 81-82.
- 4. Kanner L. Autistic disturbances of affective contact. Nervous Child 1943; 2: 217-250.
- 5. Mahoney WJ, Szatmari P, MacLean JE, et al. Reliability and accuracy of differentiating pervasive developmental disorder subtypes. J Am Acad Child Adolesc Psychiatry 1998; 37: 278-285.
- 6. Baird G, Charman T, Baron-Cohen S, et al. A screening instrument for autism at 18 months of age: a 6-year follow-up study. J Am Acad Child Adolesc Psychiatry 2000; 39: 694-702.
- 7. Fombonne E. Epidemiological trends in rates of autism. Mol Psychiatr 2002; 7: S4-S6.
- 8. Wing L, Gould J. Severe impairments of social interaction and associated abnormalities in children: epidemiology and classification. J Autism Dev Disord 1979; 9: 11-29.
- 9. Filipek PA, Accardo PJ, Baranek GT, et al. The screening and diagnosis of autistic spectrum disorders. J Autism Dev Disord 1999; 29: 439-484.
- 10. World Health Organization. The ICD-10 classification of mental and behavioural disorders: diagnostic criteria for research. Geneva: WHO, 1993.
- 11. American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 4th ed (DSM-IV). Washington, DC: American Psychiatric Association, 1994.
- 12. Medical Research Council. Review of autism research: epidemiology and causes. London: Medical Research Council, 2001.
- 13. Bristol MM, Cohen DJ, Costello EJ, et al. State of the science in autism: report to the National Institutes of Health. J Autism Dev Disord 1996; 26: 121-154.
- 14. Fombonne E. Is there an epidemic of autism? Pediatrics 2001; 107: 411-412.
- 15. Howlin P. The importance and implications of early diagnosis. Biennial National Autism Conference. Positive steps forward. Sydney: Autism Council of Australia, 2001.
- 16. Glasson EJ. The Western Australian register for autism spectrum disorders. J Paediatr Child Health 2002; 38: 321.
- 17. Buitelaar JK, van der Gaag RJ. Diagnostic rules for children with PDD-NOS and multiple complex developmental disorder. J Child Psychol Psychiatry 1998; 39: 911-919.
- 18. Elliott EJ, Nicoll A, Lynn R, et al. Rare disease surveillance: an international perspective. J Paediatr Child Health 2001; 6: 251-260.
- 19. Gazarian M, Williams K, Elliott E, et al. Evaluation of a national surveillance unit. Arch Dis Child 1999; 80: 21-27.
- 20. Australian Bureau of Statistics. Australian demographic statistics. Canberra: ABS, 2000. (Cat. no. 3101.0.)
- 21. Epi Info, version 6: A word processing, database and statistics program for epidemiology on microcomputers. Atlanta, Ga: US Centers for Disease Control and Prevention, 1994.
- 22. Chakrabarti S, Fombonne E. Pervasive developmental disorders in preschool children. JAMA 2001; 285: 3093-3099.
- 23. Bertrand J, Audrey M, Boyle C, et al. Prevalence of autism in a United States population: the Brick Township New Jersey, investigation. Pediatrics 2001; 108: 1155-1161.
- 24. Powell JE, Edwards A, Edwards M, et al. Changes in the incidence of childhood autism and other autistic spectrum disorders in preschool children from two areas of the West Midlands, UK. Dev Med Child Neurol 2000; 42: 624-628.
- 25. Kaye JA, del Mar Melero-Montes M, Jick H. Mumps, measles and rubella vaccine and the incidence of autism recorded by general practitioners: a time trend analysis. BMJ 2001; 322: 460-463.
- 26. Icasiano F, Hewson P, Machet P, et al. Childhood autism spectrum disorder in the Barwon region: a community based study. J Paediatr Child Health 2004; 40: 696-701.
- 27. Glasson EJ, Wray J. Obtaining consent affects the value of the Western Australian autism register [letter]. Med J Aust 2004; 181: 514-515. <MJA full text>
- 28. Williamson OD, Cameron PA, McNeil JJ. Medical registry governance and patient privacy. Med J Aust 2004; 181: 125-126. <MJA full text>
- 29. Tu JV, Willison DJ, Silver FL, et al. Impracticability of informed consent in the Registry of the Canadian Stroke Network. N Engl J Med 2004; 350: 1414-1421.
- 30. Smith MA, Jalaludin B, Leeder SR, Smith WT. Isn’t one institutional ethics committee’s approval enough? Med J Aust 1994; 160: 662.
- 31. Beran RG. Should there be an accredited ethics committee system for centralised review of multicentre clinical research? Med J Aust 1998; 168: 174.
Publication of your online response is subject to the Medical Journal of Australia's editorial discretion. You will be notified by email within five working days should your response be accepted.