title: The incidence of clinically diagnosed versus research-identified autism in Olmsted County, Minnesota, 1976-1997: results from a retrospective, population-based study.
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.
authors.affiliation: Department 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
authors.forename: William J
authors.initials: WJ
authors.lastname: Barbaresi
authors.forename: Robert C
authors.initials: RC
authors.lastname: Colligan
authors.forename: Amy L
authors.initials: AL
authors.lastname: Weaver
authors.forename: Slavica K
authors.initials: SK
authors.lastname: Katusic
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D001321:Autistic Disorder / Q000175:diagnosis / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008910:Minnesota / Q000453:epidemiology; D011159:Population Surveillance; D015995:Prevalence; D012189:Retrospective Studies; D017678:Sex Distribution; D055815:Young Adult
references.citation: J Autism Dev Disord. 2003 Apr;33(2):187-92
references.pmid: 12757358
references.citation: Curr Dir Psychol Sci. 2005 Apr;14(2):55-58
references.pmid: 25404790
references.citation: Arch Pediatr Adolesc Med. 2003 Jul;157(7):622-7
references.pmid: 12860781
references.citation: Mayo Clin Proc. 1996 Mar;71(3):266-74
references.pmid: 8594285
references.citation: J Child Psychol Psychiatry. 1984 Jan;25(1):35-43
references.pmid: 6607262
references.citation: J Am Acad Child Adolesc Psychiatry. 2001 Jul;40(7):820-7
references.pmid: 11437021
references.citation: J Am Acad Child Adolesc Psychiatry. 1987 Sep;26(5):700-3
references.pmid: 3499432
references.citation: Pediatrics. 2006 Apr;117(4):1438-9
references.pmid: 16585346
references.citation: JAMA. 2003 Jan 1;289(1):87-9
references.pmid: 12503982
references.citation: Br J Psychiatry. 1986 Jul;149:81-7
references.pmid: 3779317
references.citation: Ment Retard Dev Disabil Res Rev. 2002;8(3):151-61
references.pmid: 12216059
references.citation: MMWR Surveill Summ. 2007 Feb 9;56(1):1-11
references.pmid: 17287714
references.citation: Soc Psychiatry Psychiatr Epidemiol. 1992 Aug;27(4):203-10
references.pmid: 1411750
references.citation: Pediatrics. 2001 Nov;108(5):1155-61
references.pmid: 11694696
references.citation: Arch Pediatr Adolesc Med. 2005 Jan;159(1):37-44
references.pmid: 15630056
references.citation: Arch Pediatr Adolesc Med. 2003 Jul;157(7):619-21
references.pmid: 12860780
references.citation: JAMA. 2003 Jan 1;289(1):49-55
references.pmid: 12503976
references.citation: Am J Psychiatry. 1989 Feb;146(2):194-9
references.pmid: 2783539
references.citation: Mayo Clin Proc. 1998 Nov;73(11):1053-61
references.pmid: 9818038
references.citation: MMWR Surveill Summ. 2007 Feb 9;56(1):12-28
references.pmid: 17287715
references.citation: Pediatrics. 2005 Mar;115(3):e277-82
references.pmid: 15741352