title: Trends in autism prevalence: diagnostic substitution revisited.
abstract: There has been little evidence to support the hypothesis that diagnostic substitution may contribute to increases in the administrative prevalence of autism. We examined trends in assignment of special education codes to British Columbia (BC) school children who had an autism code in at least 1 year between 1996 and 2004, inclusive. The proportion of children with an autism code increased from 12.3/10,000 in 1996 to 43.1/10,000 in 2004; 51.9% of this increase was attributable to children switching from another special education classification to autism (16.0/10,000). Taking into account the reverse situation (children with an autism code switching to another special education category (5.9/10.000)), diagnostic substitution accounted for at least one-third of the increase in autism prevalence over the study period.
authors.affiliation: Department of Community Health and Epidemiology, Queen's University, c/o Ongwanada Resource Centre, 191 Portsmouth Avenue, Kingston, ON, Canada, K7M 8A6.
authors.forename: Helen
authors.initials: H
authors.lastname: Coo
authors.forename: Hélène
authors.initials: H
authors.lastname: Ouellette-Kuntz
authors.forename: Jennifer E V
authors.initials: JE
authors.lastname: Lloyd
authors.forename: Liza
authors.initials: L
authors.lastname: Kasmara
authors.forename: Jeanette J A
authors.initials: JJ
authors.lastname: Holden
authors.forename: M E Suzanne
authors.initials: ME
authors.lastname: Lewis
mesh_terms: D001321:Autistic Disorder / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D001955:British Columbia; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D004519:Education, Special / Q000639:trends; D006801:Humans; D015994:Incidence; D012017:Referral and Consultation / Q000639:trends