Journal of Autism and Developmental Disorders

, Volume 39, Issue 3, pp 464–470

The Incidence of Clinically Diagnosed Versus Research-Identified Autism in Olmsted County, Minnesota, 1976–1997: Results from a Retrospective, Population-Based Study

Authors

    • Department of Pediatric and Adolescent Medicine, Division of Developmental and Behavioral PediatricsCollege of Medicine, Mayo Clinic
    • Mayo Clinic Dana Child Development and Learning Disorders ProgramCollege of Medicine, Mayo Clinic
  • Robert C. Colligan
    • Department of Psychiatry and PsychologyCollege of Medicine, Mayo Clinic
  • Amy L. Weaver
    • Department of Health Sciences Research, Division of BiostatisticsCollege of Medicine, Mayo Clinic
  • Slavica K. Katusic
    • Mayo Clinic Dana Child Development and Learning Disorders ProgramCollege of Medicine, Mayo Clinic
    • Department of Health Sciences Research, Division of EpidemiologyCollege of Medicine, Mayo Clinic
Original Paper

DOI: 10.1007/s10803-008-0645-8

Cite this article as:
Barbaresi, W.J., Colligan, R.C., Weaver, A.L. et al. J Autism Dev Disord (2009) 39: 464. doi:10.1007/s10803-008-0645-8

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 ≤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.

Keywords

AutismEpidemiologyAutistic disorderIncidencePopulation-based

Copyright information

© Springer Science+Business Media, LLC 2008