05/18/2011 Prevalence of Parent-Reported Diagnosis of Autism Spectrum (ASD) Disorder Among Children in the US, 2007

Resident: J. Hencler
Date: 05/18/2011

Article title: Prevalence of Parent-Reported Diagnosis of Autism Spectrum (ASD) Disorder Among Children in the US, 2007

Author(s): Kogan et al

Journal: Pediatrics Vol 124, No 5, 11/2009
Type of Article: Survey

Main Purpose: To report the prevalence of ASD.

Background:
ASD is a grp of neurodevelopmental disorders comprising autism and 2 related less severe disorders: Aspergers and Pervasive developmental disorder not otherwise specified (PDD-NOS). Characteristics include impairments in social interactions and communication as well as restricted, repetitive, and stereotyped patterns of behavior. Recent US studies report prevalences ranging from 50-90 in 10000 children w/ notable variation in child age, gender, ethnicity, and socioeconomic status.

Overview of method of research:
Random-digit-dial telephone survey was conducted on the health of children <18yo based on interview with a parent. 91642 interviews were completed and analyses for this study were limited to 78037 children who were 3-17yo. Interview questions asked: currently dx w/ ASD? Ever dx w/ ASD, but not currently dx? Never dx w/ ASD? Severity of ASD? Demographic/socioeconomic characteristics? Health care experiences?

Findings:
Prevalence of ASD was 110 per 10000 children. ASD dx most common to least common age grps: 9-11yo>>6-8yo>15-17yo. Boys found to have ASD 4X more than girls. Caucasians most common to have ASD. A very high % of children w/ ASD and children w/ past but not current dx of ASD had co-occuring conditions including ADD, ADHD, anxiety, behavior disorders, depression, and/or developmental delay. Those w/ severe or moderate ASD were more commonly had at 1 of the 5 co-occuring conditions. Children w/ current ASD had better access to care, however, children w/ current ASD had poorer perceived quality of care.

Key points in the article discussion:
In 2007, 1.1% of US children 3-17yo were reported to have ASD dx. Nearly 40% of all children reported to have ever had a dx of ASD, a parent reported a past dx but not a current dx. Although ASD dx at young ages should still be valid at a later age, difficulty with and a lack of precision in dx ASD at a very young age could result in a minority of children who no longer meet ASD criteria as they age. Some explanations include 1) ASD may have been initially suspected on the basis of a developmental screening but subsequently ruled out and never truly dx, 2) some children w/ developmental delay, MR, and learning disabilities may have been initially classified as ASD to facilitate receipt of needed services, such as early intervention programs, and 3) b/c parent reported current ASD was not externally validated, the parents may have responded no b/c their child no longer receives special ed or other autism-specific services. Several previous studies have shown that the ave age of dx is decreasing, which leads to an increase in prevalence at any 1 pt in time. Important changes in the 1990s included broadening dx criteria for ASD, increase in dx services, greater awareness, and growing acceptance that autism can co-occur w/ other conditions have all played a role in the continued rise in ASD prevalence rates. The AAP released 2 reports recommending earlier and more frequent surveillance for ASD and more aggressive educational and behavioral interventions. These recommendations reflect the recognition that earlier ID and intensive intervention can improve functioning.

Summary of conclusions:
The ASD prevalence found in this survey was higher than previous US estimates. More inclusive survey questions, increased population awareness, and improved screening and ID by providers may partly explain these findings.