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J Autism Dev Disord. 2009 Mar;39(3):464-70. doi: 10.1007/s10803-008-0645-8. Epub 2008 Sep 13.

The incidence of clinically diagnosed versus research-identified autism in Olmsted County, Minnesota, 1976-1997: results from a retrospective, population-based study.

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  • 1Department of Pediatric and Adolescent Medicine, Division of Developmental and Behavioral Pediatrics, College of Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. barbaresi.william@mayo.edu

Abstract

Autism prevalence studies have often relied on administrative prevalence or clinical diagnosis as case-identification strategies. We report the incidence of clinical diagnoses of autism spectrum disorders (ASD), versus research-identified autism among residents of Olmsted County, Minnesota, age < or =21 years, from 1976-1997. The incidence of clinically diagnosed ASD (with 95% CI) was 1.5 per 100,000 (0.0-3.7) in 1980-1983 and 33.1 (22.8-43.3) in 1995-1997, a 22.1-fold increase. In contrast, the incidence of research-identified autism increased from 5.5 (1.4-9.5) per 100,000 to 44.9 (32.9-56.9), an 8.2-fold increase. Only 46.8% of research-identified cases received a clinical diagnosis of ASD. These findings demonstrate the potential for misleading interpretation of results from epidemiologic studies that rely on clinical diagnosis of autism to identify cases.

PMID:
18791815
PMCID:
PMC2859841
DOI:
10.1007/s10803-008-0645-8
[PubMed - indexed for MEDLINE]
Free PMC Article
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