How Many Children have an Autism Spectrum Disorder?

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Beverley Weaver
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1 How Many Children have an Autism Spectrum Disorder? Cathy Rice, Ph.D. National Center on Birth Defects and Developmental Disabilities Centers for Disease Control and Prevention The findings and conclusions in this presentation are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention

IDEA, Part B, 1992-93 to 2000-01, 6-21 years Children with Autism Served Quarterly Trends in Number of Persons with Autism Added to the System (1994-2004) 1 2 3 4 5 6 7 8 9 10 11 Year Number

2 Concerns Over Increases of Children with Autism Epidemiologic Data - Prevalence Studies Low Incidence Disorder? (about 1 per 2,000 children) Service Provider Data Numbers of individuals in services Number Increased per Quarter Number of Children with Autism Served under IDEA, Part B, to , 6-21 years Children with Autism Served Quarterly Trends in Number of Persons with Autism Added to the System ( ) Year Number ( ) (n=49) (n=51) (n=52) (n=52) (n=52) (n=52) (n=52) (n=52) Fourth Qtr Third Qtr Second Qtr First Qtr (n=52) School Year (# states reporting) *includes DC & PR

setting Who else may have the condition(s)?

3 How do we know who has an ASD? It is clear that more children are identified with an Autism Spectrum Disorder (ASD) than in the past. Children receiving services Children diagnosed in a medical or clinical setting Who else may have the condition(s)? Little population-based data of the features of ASDs Behaviorally-defined Prevalence studies involve population screening Direct screening who participates? Records-based screening

4 Autism Around the World Found in all communities around the world? Most studies from industrialized countries (US, Canada, European, Scandanavian, Japanese) Increasing awareness of developmental disabilities and autism in developing countries. Countries with autism societies (2008)

Prevalence of ASDs Autism spectrum disorders (ASDs) are a group of developmental disabilities defined by significant impairments in social interaction and communication and the presence of unusual

5 Prevalence of ASDs Autism spectrum disorders (ASDs) are a group of developmental disabilities defined by significant impairments in social interaction and communication and the presence of unusual behaviors and interests with symptoms typically present before the age of 3 years. Prior to 1990: 1 in 2,000 children Mid 90 s: 1 in 500 Mid 00 s: 1 in 150 Now: some studies showing about 1% of children with an ASD Since ASDs are defined by behavioral observation, determining prevalence and changes over time is challenging.

6 CDC Prevalence of ASDs Metropolitan Atlanta Developmental Disabilities Surveillance Program MADDSP National Autism and Developmental Disabilities Monitoring (ADDM) Network

Records-based Surveillance Identify multiple

for descriptions ( triggers ) specific to ASD and CP,

Abstract compile evaluation information.

7 Records-based Surveillance Identify multiple educational and health evaluation sources Screen files for descriptions ( triggers ) specific to ASD and CP, standardized test scores for ID, HL and VI. Abstract compile evaluation information. Clinician review based on DSM-IV TR criteria if a child has an ASD for prevalence purposes.

9 How many children have an ASD? According to CDC February 2007, the first ADDM Network report Between 1 in 100 to 1 in with an average of 1 in 150 children with ASD (retrospective view of years 2000 and 2002). December nd report Retrospective view of 2006 (born 1998) for 11 sites 2004 (born 1996) optional year for 8 sites Prevalence changes in 10 ADDM sites from the years 2002 to 2006 Authors: Autism and Developmental Disabilities Monitoring (ADDM) Network Principal Investigators

10 ADDM Network Overall Prevalence Surv Year Birth Year # sites 8-year-old Population 8-year-old children with an ASD Average Prev / 1,000 Range ,761 1, ,578 2, ,335 1, ,038 2, (14) In process

11 Overall Identified ASD Prevalence Average across all 11 sites of 9.0 per 1,000, approaching 1% of 8 year-old children, about 1 in every 110 children with an ASD From 1 in 80 to 1 in 240 From 4.2 (FL) to 12.1 per 1,000 in AZ and MO

12 ADDM 2006 Surveillance Year Prevalence by Sex, Race or Ethnicity Average of 1 in 70 males and 1 in 315 females (4.5:1 ratio) White non-hispanic children have highest prevalence with average of 1 on 101 (9.9 in 1,000) ranging from 3.4 to 14.8 Black, non-hispanic: average of 1 in 139 children (7.2 per 1,000) ranging from 1.6 to 12.9 Hispanic: average of 1 in 169 children(5.9 per 1,000), ranging from 0.6 to 8.3

developmental concern before the age of 2 years Average age of earliest ASD diagnosis was

13 Developmental Concerns and Age of Earliest Documented ASD Diagnosis 13 30% of children had a reported developmental regression by 24 months of age 70-95% with a documented developmental concern before the age of 2 years Average age of earliest ASD diagnosis was 4 years, 6 months; ranging from 3 years, 6 months to 5 years (no real change from earlier years)

14 ADDM 2006: Special Education % in Special Education % in Autism Eligibility 83.7 Percent of ASD case children Arizona Colorado Georgia Maryland North Carolina South Carolina

15 Changes in ASD Prevalence 10 sites participated in 2002 and 2006 surveillance years Children born in 1994 and 1998

16 Percent change in identified ASD prevalence from 2002 to 2006 Overall ASD Prevalence ADDM Network MADDSP % % Male Female White NH Black NH Hispanic 91 4 IQ IQ = IQ>

Trends in period prevalence for 5 serious DDs, MADDSP 1991-2006 18 16 14 15.

17 Trends in period prevalence for 5 serious DDs, MADDSP Intellectual Disability Autism Spectrum Disorder Cerebral Palsy Hearing Loss Vision Impairment Prevalence per 1, Surveillance Year

18 Why is the identified prevalence of ASD increasing from 2002 to 2006 in ADDM? No single explanation -multiple factors at play Identification issues which contributed to small increases across sites: more evaluation records (4 vs. 5) better quality of documentation some sites able to locate more records some sites had a more stable population some sites better identification of Hispanic children (AZ) some sites more identification of children without cognitive impairment Unexplained Could be additional identification issues Possible that there is a true increase in risk Likely a combination of all of the above Still in the midst of a changing landscape Need to continue monitoring over time to follow trends Further analyses to sort out factors noted above

Implications ASDs are an important public health issue. Prevalence estimates can be used to plan policy, educational, and intervention services needs for persons with ASDs.

19 Implications ASDs are an important public health issue. Prevalence estimates can be used to plan policy, educational, and intervention services needs for persons with ASDs. A coordinated and collaborative response is needed to: Better understand trends over time; Intensify search for risk; Improve early identification and access to intervention; Better understand how to intervene to help reduce the debilitating symptoms of ASDs; Address the many needs of affected persons and to provide coordinated support services which improve daily functioning and long-term life outcomes.

gov/mmwr Updated autism website www.cdc.

20 For more information ADDM Reports in CDC s MMWR Surveillance Summaries Updated autism website Learn the Signs. Act Early. Learn the Signs. Act Early.

Lessons from Population-Based Surveillance for ASD

Lessons from Population-Based Surveillance for ASD Marshalyn Yeargin-Allsopp, MD Medical Epidemiologist Developmental Disabilities Branch National Center on Birth Defects and Developmental Disabilities