Advertisement

Journal of Autism and Developmental Disorders

, Volume 37, Issue 10, pp 1941–1948 | Cite as

Trends in Special Education Code Assignment for Autism: Implications for Prevalence Estimates

  • Hélène Ouellette-KuntzEmail author
  • Helen Coo
  • Jennifer E. V. Lloyd
  • Liza Kasmara
  • Jeanette J. A. Holden
  • M. E. Suzanne Lewis
Original Paper

Abstract

There is considerable controversy over reasons for observed increases in the prevalence of autism spectrum disorders. We examined trends in British Columbia education database coding of children with autism from 1996 to 2004. There was a significant linear increase in autism prevalence. The proportion of children identified by age 6 increased significantly from 1996 to 1999. When we calculated prevalence assuming onset prior to age 3, previously unidentified cases, particularly among girls in 1996 and 1997, accounted for substantial increases in estimated prevalence. The magnitude of under-identification decreased from 1996 to 2000, and rose slightly in 2001. Analyses of prevalence trends must take into account effects of earlier age at identification and inclusion of previously undetected cases on prevalence estimates.

Keywords

Autism autistic disorder prevalence trends special education Edudata Canada British Columbia Ministry of Education 

Notes

Acknowledgment

We wish to thank Ms. Nancy Walt, Ms. Caroline Ponsford and Ms. Claudia Roch of the British Columbia Ministry of Education, and Dr. Victor Glickman, Director of Edudata Canada, for providing us with access to the information resources of the British Columbia Ministry of Education through Edudata Canada that were integral to this study. We also wish to thank Ms. Rachel Lomas, a Life Sciences student at Queen’s University, for her assistance with the preparation of this manuscript. We are grateful to the members of the Autism Spectrum Disorders–Canadian-American Research Consortium (ASD-CARC; Jeanette J.A. Holden, principal investigator) for their work on the grant proposal that led to the funding of this and other ASD-CARC projects, and to other members of the ASD-CARC Epidemiology Project team for their contribution to the overall project. Members of these groups are listed on the ASD-CARC’s website at www.autismresearch.ca. This work was supported by a CIHR Interdisciplinary Health Research Team grant (RT-43820) to the ASD-CARC. Dr. Suzanne Lewis sincerely appreciates the support provided by the CIHR Institute of Genetics Clinician Investigator (2003–2005) and Michael Smith Foundation for Health Research Scholar Programs (2005–2010). The findings and interpretations expressed herein are those of the authors, and do not necessarily reflect the opinions of the British Columbia Ministry of Education or of Edudata Canada.

References

  1. Abramson, J. H., & Gahlinger, P. M. (2001). Computer program for epidemiologists: PEPI Version 4.0 (Version 4.0). Salt Lake City: Sagebrush Press.Google Scholar
  2. American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (DSM-IV) (4th ed.). Washington, DC: American Psychiatric Association.Google Scholar
  3. Autism Society Canada (2004). Canadian autism research and strategy agendas released in White Paper from Autism Society Canada. Retrieved May 30, 2005 from http://autismsocietycanada.ca/pdf_word/mediafinal.pdf.Google Scholar
  4. Baird, G., Charman, T., Baron-Cohen, S., Cox, A., Swettenham, J., Wheelwright, S. et al. (2000). A screening instrument for autism at 18 months of age: A 6-year follow-up study. Journal of the American Academy of Child and Adolescent Psychiatry, 39, 694–702.PubMedCrossRefGoogle Scholar
  5. Baker, H. C. (2002). A comparison study of autism spectrum disorder referrals 1997 and 1989. Journal of Autism and Developmental Disorders, 32, 121–125.PubMedCrossRefGoogle Scholar
  6. Bertrand, J., Mars, A., Boyle, C., Bove, F., Yeargin-Allsopp, M., & Decouflé, P. (2001). Prevalence of autism in a United States population: The Brick Township, New Jersey, investigation. Pediatrics, 108, 1155–1161.PubMedCrossRefGoogle Scholar
  7. British Columbia Ministry of Education, S. P. B. (2000). Teaching students with autism. A resource guide for schools. [RB0102]. Retrieved August 26, 2005, from http://www.bced.gov.bc.ca/specialed/docs/autism.pdf.Google Scholar
  8. Chakrabarti, S., & Fombonne, E. (2001). Pervasive developmental disorders in preschool children. The Journal of the American Medical Association, 285, 3093–3099.CrossRefGoogle Scholar
  9. Croen, L. A., Grether, J. K., Hoogstrate, J., & Selvin, S. (2002). The changing prevalence of autism in California. Journal of Autism and Developmental Disorders, 32, 207–215.PubMedCrossRefGoogle Scholar
  10. Dales, L., Hammer, S. J., Smith, N. J. (2001). Time trends in autism and in MMR immunization coverage in California. The Journal of the American Medical Association, 285, 1183–1185.CrossRefGoogle Scholar
  11. Fombonne, E. (2003). Epidemiological surveys of autism and other pervasive developmental disorders: an update. Journal of Autism and Developmental Disorders, 33, 365–382.PubMedCrossRefGoogle Scholar
  12. Gurney, J. G., Fritz, M. S., Ness, K. K., Sievers, P., Newschaffer, C. J., & Shapiro, E. G. (2003). Analysis of prevalence trends of autism spectrum disorder in Minnesota. Archives of Pediatric and Adolescent Medicine, 157, 622–627.CrossRefGoogle Scholar
  13. Keen, D., & Ward, S. (2004). Autistic spectrum disorder: a child population profile. Autism: the international journal of research and practice, 8, 39–48.Google Scholar
  14. Laidler, J. R. (2005). US Department of Education data on “autism” are not reliable for tracking autism prevalence. Pediatrics, 116, e120-e124.PubMedCrossRefGoogle Scholar
  15. Lauritsen, M. B., Pedersen, C. B., & Mortensen, P. B. (2004). The incidence and prevalence of pervasive developmental disorders: a Danish population-based study. Psychological Medicine, 34, 1339–1346.PubMedCrossRefGoogle Scholar
  16. Lingam, R., Simmons, A., Andrews, N., Miller, E., Stowe, J., & Taylor, B. (2003). Prevalence of autism and parentally reported triggers in a north east London population. Archives of Disease in Childhood, 88, 666–670.PubMedCrossRefGoogle Scholar
  17. Lord, C., Schopler, E., & Revicki, D. (1982). Sex differences in autism. Journal of Autism and Developmental Disorders, 12, 317–330.PubMedCrossRefGoogle Scholar
  18. Mahoney, W. J., Szatmari, P., MacLean, J. E., Bryson, S., Bartolucci, G., Walter, S. D. et al. (1998). Reliability and accuracy of differentiating pervasive developmental disorder subtypes. Journal of the American Academy of Child and Adolescent Psychiatry, 37, 278–285.PubMedCrossRefGoogle Scholar
  19. McLennan, J. D., Lord, C., & Schopler, E. (1993). Sex differences in higher functioning people with autism. Journal of Autism and Developmental Disorders, 23, 217–227.PubMedCrossRefGoogle Scholar
  20. Newschaffer, C. J., Falb, M. D., & Gurney, J. G. (2005). National autism prevalence trends from United States special education data. Pediatrics, 115, e277-e282.PubMedCrossRefGoogle Scholar
  21. Prior, M. (2003). Is there an increase in the prevalence of autism spectrum disorders? Journal of Paediatrics and Child Health, 39, 81–82.PubMedCrossRefGoogle Scholar
  22. Rodier, P. M. (2000). The early origins of autism. Scientific American, 282, 56–63.PubMedCrossRefGoogle Scholar
  23. Rutter, M., & Schopler, E. (1987). Autism and pervasive developmental disorders: concepts and diagnostic issues. Journal of Autism and Developmental Disorders, 17, 159–181.PubMedCrossRefGoogle Scholar
  24. Stokstad, E. (2001). Development. Scant evidence for an epidemic of autism. Science, 294, 35.Google Scholar
  25. The Canadian Autism Intervention Research Network (2002). Family Link. Research Studies of Autism/PDD. Retrieved October 20, 2005, from http://www.geocities.com/autismandpdd/newltr4.htm.Google Scholar
  26. Tsai, L., Stewart, M. A., & August, G. (1981). Implication of sex differences in the familial transmission of infantile autism. Journal of Autism & Developmental Disorders, 11, 165–173.CrossRefGoogle Scholar
  27. Wing, L. (1981). Sex ratios in early childhood autism and related conditions. Psychiatry Research, 5, 129–137.PubMedCrossRefGoogle Scholar
  28. Wing, L., & Potter, D. (2002). The epidemiology of autistic spectrum disorders: is the prevalence rising? Mental Retardation and Developmental Disabilities Research Reviews, 8, 151–161.PubMedCrossRefGoogle Scholar
  29. Yeargin-Allsopp, M., Rice, C., Karapurkar, T., Doernberg, N., Boyle, C., & Murphy, C. (2003). Prevalence of autism in a US metropolitan area. The Journal of the American Medical Association, 289, 49–55.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2006

Authors and Affiliations

  • Hélène Ouellette-Kuntz
    • 1
    Email author
  • Helen Coo
    • 2
  • Jennifer E. V. Lloyd
    • 3
    • 4
  • Liza Kasmara
    • 3
    • 5
  • Jeanette J. A. Holden
    • 2
  • M. E. Suzanne Lewis
    • 3
  1. 1.Queen’s UniversityKingstonCanada
  2. 2.Queen’s UniversityKingstonCanada
  3. 3.University of British ColumbiaVancouverCanada
  4. 4.Human Early Learning Partnership (HELP)VancouverCanada
  5. 5.Columbia UniversityNew YorkUSA

Personalised recommendations