Diagnostic Change Increased the Prevalence of Autism

Increased autism prevalence rates have generated considerable concern. However, the contribution of changes in diagnostic practices to increased prevalence rates has not been thoroughly examined. Debates over the role of diagnostic substitution also continue. California has been an important test case in these controversies. The objective of this study was to determine the extent to which the increased prevalence of autism in California has been driven by changes in diagnostic practices, diagnostic substitution and diagnostic accretion. Changes in practices for diagnosing autism have had a substantial effect on autism caseloads, accounting for one-quarter of the observed increase in prevalence in California between 1992 and 2005.


Read our paper: King, M. & Bearman, P. (2009). Diagnostic Change and Increased Prevalence of Autism. International Journal of Epidemiology, Volume 38, Issue 5:1224-1234.

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