Skip to main content

Advertisement

Log in

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

  • Original Paper
  • Published:
Journal of Autism and Developmental Disorders Aims and scope Submit manuscript

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.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Subscribe and save

Springer+ Basic
EUR 32.99 /Month
  • Get 10 units per month
  • Download Article/Chapter or Ebook
  • 1 Unit = 1 Article or 1 Chapter
  • Cancel anytime
Subscribe now

Buy Now

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3

Similar content being viewed by others

References

  • 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 

  • American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (DSM-IV) (4th ed.). Washington, DC: American Psychiatric Association.

    Google Scholar 

  • 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.

  • 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.

    Article  PubMed  CAS  Google Scholar 

  • Baker, H. C. (2002). A comparison study of autism spectrum disorder referrals 1997 and 1989. Journal of Autism and Developmental Disorders, 32, 121–125.

    Article  PubMed  Google Scholar 

  • 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.

    Article  PubMed  CAS  Google Scholar 

  • 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.

  • Chakrabarti, S., & Fombonne, E. (2001). Pervasive developmental disorders in preschool children. The Journal of the American Medical Association, 285, 3093–3099.

    Article  CAS  Google Scholar 

  • 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.

    Article  PubMed  Google Scholar 

  • 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.

    Article  CAS  Google Scholar 

  • Fombonne, E. (2003). Epidemiological surveys of autism and other pervasive developmental disorders: an update. Journal of Autism and Developmental Disorders, 33, 365–382.

    Article  PubMed  Google Scholar 

  • 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.

    Article  Google Scholar 

  • 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 

  • Laidler, J. R. (2005). US Department of Education data on “autism” are not reliable for tracking autism prevalence. Pediatrics, 116, e120-e124.

    Article  PubMed  Google Scholar 

  • 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.

    Article  PubMed  CAS  Google Scholar 

  • 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.

    Article  PubMed  CAS  Google Scholar 

  • Lord, C., Schopler, E., & Revicki, D. (1982). Sex differences in autism. Journal of Autism and Developmental Disorders, 12, 317–330.

    Article  PubMed  CAS  Google Scholar 

  • 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.

    Article  PubMed  CAS  Google Scholar 

  • 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.

    Article  PubMed  CAS  Google Scholar 

  • Newschaffer, C. J., Falb, M. D., & Gurney, J. G. (2005). National autism prevalence trends from United States special education data. Pediatrics, 115, e277-e282.

    Article  PubMed  Google Scholar 

  • Prior, M. (2003). Is there an increase in the prevalence of autism spectrum disorders? Journal of Paediatrics and Child Health, 39, 81–82.

    Article  PubMed  CAS  Google Scholar 

  • Rodier, P. M. (2000). The early origins of autism. Scientific American, 282, 56–63.

    Article  PubMed  CAS  Google Scholar 

  • Rutter, M., & Schopler, E. (1987). Autism and pervasive developmental disorders: concepts and diagnostic issues. Journal of Autism and Developmental Disorders, 17, 159–181.

    Article  PubMed  CAS  Google Scholar 

  • Stokstad, E. (2001). Development. Scant evidence for an epidemic of autism. Science, 294, 35.

  • 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.

  • 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.

    Article  CAS  Google Scholar 

  • Wing, L. (1981). Sex ratios in early childhood autism and related conditions. Psychiatry Research, 5, 129–137.

    Article  PubMed  CAS  Google Scholar 

  • 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.

    Article  PubMed  Google Scholar 

  • 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.

    Article  Google Scholar 

Download references

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.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Hélène Ouellette-Kuntz.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Ouellette-Kuntz, H., Coo, H., Lloyd, J.E.V. et al. Trends in Special Education Code Assignment for Autism: Implications for Prevalence Estimates. J Autism Dev Disord 37, 1941–1948 (2007). https://doi.org/10.1007/s10803-006-0326-4

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10803-006-0326-4

Keywords

Navigation