Jon Baio

Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years--Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2012

PROBLEM/CONDITION Autism spectrum disorder (ASD). PERIOD COVERED 2012. DESCRIPTION OF SYSTEM The Autism and Developmental Disabilities Monitoring (ADDM) Network is an active surveillance system that provides estimates of the prevalence and characteristics of ASD among children aged 8 years whose parents or guardians reside in 11 ADDM Network sites in the United States (Arkansas, Arizona, Colorado, Georgia, Maryland, Missouri, New Jersey, North Carolina, South Carolina, Utah, and Wisconsin). Surveillance to determine ASD case status is conducted in two phases. The first phase consists of screening and abstracting comprehensive evaluations performed by professional service providers in the community. Data sources identified for record review are categorized as either 1) education source type, including developmental evaluations to determine eligibility for special education services or 2) health care source type, including diagnostic and developmental evaluations. The second phase involves the review of all abstracted evaluations by trained clinicians to determine ASD surveillance case status. A child meets the surveillance case definition for ASD if one or more comprehensive evaluations of that child completed by a qualified professional describes behaviors that are consistent with the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision diagnostic criteria for any of the following conditions: autistic disorder, pervasive developmental disorder-not otherwise specified (including atypical autism), or Asperger disorder. This report provides ASD prevalence estimates for children aged 8 years living in catchment areas of the ADDM Network sites in 2012, overall and stratified by sex, race/ethnicity, and the type of source records (education and health records versus health records only). In addition, this report describes the proportion of children with ASD with a score consistent with intellectual disability on a standardized intellectual ability test, the age at which the earliest known comprehensive evaluation was performed, the proportion of children with a previous ASD diagnosis, the specific type of ASD diagnosis, and any special education eligibility classification. RESULTS For 2012, the combined estimated prevalence of ASD among the 11 ADDM Network sites was 14.6 per 1,000 (one in 68) children aged 8 years. Estimated prevalence was significantly higher among boys aged 8 years (23.6 per 1,000) than among girls aged 8 years (5.3 per 1,000). Estimated ASD prevalence was significantly higher among non-Hispanic white children aged 8 years (15.5 per 1,000) compared with non-Hispanic black children (13.2 per 1,000), and Hispanic (10.1 per 1,000) children aged 8 years. Estimated prevalence varied widely among the 11 ADDM Network sites, ranging from 8.2 per 1,000 children aged 8 years (in the area of the Maryland site where only health care records were reviewed) to 24.6 per 1,000 children aged 8 years (in New Jersey, where both education and health care records were reviewed). Estimated prevalence was higher in surveillance sites where education records and health records were reviewed compared with sites where health records only were reviewed (17.1 per 1,000 and 10.7 per 1,000 children aged 8 years, respectively; p<0.05). Among children identified with ASD by the ADDM Network, 82% had a previous ASD diagnosis or educational classification; this did not vary by sex or between non-Hispanic white and non-Hispanic black children. A lower percentage of Hispanic children (78%) had a previous ASD diagnosis or classification compared with non-Hispanic white children (82%) and with non-Hispanic black children (84%). The median age at earliest known comprehensive evaluation was 40 months, and 43% of children had received an earliest known comprehensive evaluation by age 36 months. The percentage of children with an earliest known comprehensive evaluation by age 36 months was similar for boys and girls, but was higher for non-Hispanic white children (45%) compared with non-Hispanic black children (40%) and Hispanic children (39%). INTERPRETATION Overall estimated ASD prevalence was 14.6 per 1,000 children aged 8 years in the ADDM Network sites in 2012. The higher estimated prevalence among sites that reviewed both education and health records suggests the role of special education systems in providing comprehensive evaluations and services to children with developmental disabilities. Disparities by race/ethnicity in estimated ASD prevalence, particularly for Hispanic children, as well as disparities in the age of earliest comprehensive evaluation and presence of a previous ASD diagnosis or classification, suggest that access to treatment and services might be lacking or delayed for some children. PUBLIC HEALTH ACTION The ADDM Network will continue to monitor the prevalence and characteristics of ASD among children aged 8 years living in selected sites across the United States. Recommendations from the ADDM Network include enhancing strategies to 1) lower the age of first evaluation of ASD by community providers in accordance with the Healthy People 2020 goal that children with ASD are evaluated by age 36 months and begin receiving community-based support and services by age 48 months; 2) reduce disparities by race/ethnicity in identified ASD prevalence, the age of first comprehensive evaluation, and presence of a previous ASD diagnosis or classification; and 3) assess the effect on ASD prevalence of the revised ASD diagnostic criteria published in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.

Timing of Identification Among Children With an Autism Spectrum Disorder: Findings From a Population-Based Surveillance Study

OBJECTIVE At what age are children with an autism spectrum disorder (ASD) identified by community providers? What factors influence the timing of when children are identified with ASDs? This study examined the timing of when children with ASDs are identified. METHOD Data came from 13 sites participating in the Centers for Disease Control and Preventions 2002 multisite ongoing autism surveillance program, the Autism and Developmental Disabilities Monitoring Network. Survival analysis was used to examine factors that influence the timing of community-based identification and diagnosis. RESULT Data from health and education records reveal that the median age of identification was 5.7 years (SE 0.08 years). Parametric survival models revealed that several factors were associated with a younger age of identification: being male, having an IQ of 70 or lower, and having experienced developmental regression. Significant differences in the age of identification among the 13 sites were also discovered. CONCLUSIONS The large gap between the age at which children can be identified and when they actually are identified suggests a critical need for further research, innovation, and improvement in this area of clinical practice.

Examination of the time between first evaluation and first autism spectrum diagnosis in a population-based sample.

ABSTRACT. Early identification of young children with an autism spectrum disorder (ASD) can lead to earlier entry into intervention programs that support improved developmental outcomes. The purpose of the present study was to examine identification and diagnostic patterns of children with ASD who live in a large metropolitan area. One hundred fifteen 8-year-old children diagnosed with ASD were identified from a population-based surveillance system at the Centers for Disease Control and Prevention. Primary variables of interest included earliest age of evaluation and earliest age of diagnosis identified from surveillance records, type of initial ASD diagnosis, evaluation sources that documented first ASD diagnosis, characteristics of professionals assigning first ASD diagnosis, and diagnostic tools used to aid the diagnostic process. We found that children with ASD identified by the surveillance system were initially evaluated at a mean of 48 months but were not diagnosed with ASD until a mean age of 61 months. There were no differences in timing of diagnosis based on sex or racial/ethnic classification, although degree of impairment associated with ASD predicted mean age at first evaluation and mean age at first ASD diagnosis. Most children were identified at nonschool sources, such as hospitals and clinics; 24% of the sample did not receive a documented ASD diagnosis until entering school. Most practitioners (70%) did not use a diagnostic instrument when assigning the first ASD diagnosis. Implications for early identification of ASD are discussed.

Prevalence and Characteristics of Autism Spectrum Disorder Among 4-Year-Old Children in the Autism and Developmental Disabilities Monitoring Network.

Objective: Early identification of children with autism spectrum disorder (ASD) facilitates timely access to intervention services. Yet, few population-based data exist on ASD identification among preschool-aged children. The authors aimed to describe ASD prevalence and characteristics among 4-year-old children in 5 of 11 sites participating in the 2010 Autism and Developmental Disabilities Monitoring Network. Method: Children with ASD were identified through screening of health and education records for ASD indicators, data abstraction and compilation for each child, and clinician review of records. ASD prevalence estimates, ages at first evaluation and ASD diagnosis, cognitive test scores, and demographics were compared for 4-year-old children and 8-year-old children living in the same areas. Results: Among 58,467 children in these 5 sites, 4-year-old ASD prevalence was 13.4 per 1000, which was 30% lower than 8-year-old ASD prevalence. Prevalence of ASD without cognitive impairment was 40% lower among 4-year-olds compared with 8-year-olds, but prevalence of ASD with cognitive impairment was 20% higher among 4-year-olds compared with 8-year-olds. Among 4-year-olds with ASD, female and non-Hispanic white children were more likely to receive their first comprehensive evaluation by age 36 months compared with male and non-Hispanic black children, respectively. Among children diagnosed with ASD by age 48 months, median age at first comprehensive evaluation was 27 months for 4-year-olds compared with 32 months for 8-year-olds. Conclusion: Population-based ASD surveillance among 4-year-old children provides valuable information about the early identification of children with ASD and suggests progression toward lowering the age of first ASD evaluation within participating Autism and Developmental Disabilities Monitoring communities.

Developmental regression in children with an autism spectrum disorder identified by a population-based surveillance system

This study evaluated the phenomenon of autistic regression using population-based data. The sample comprised 285 children who met the autism spectrum disorder (ASD) case definition within an ongoing surveillance program. Results indicated that children with a previously documented ASD diagnosis had higher rates of autistic regression than children who met the ASD surveillance definition but did not have a clearly documented ASD diagnosis in their records (17—26 percent of surveillance cases). Most children regressed around 24 months of age and boys were more likely to have documented regression than girls. Half of the children with regression had developmental concerns noted prior to the loss of skills. Moreover, children with autistic regression were more likely to show certain associated features, including cognitive impairment.These data indicate that some children with ASD experience a loss of skills in the first few years of life and may have a unique symptom profile.

Changes in autism spectrum disorder prevalence in 4 areas of the United States

BACKGROUND We sought to describe autism spectrum disorder (ASD) population characteristics and changes in identified prevalence across 3 time periods. METHODS Children with a potential ASD were identified through records abstraction at multiple sources with clinician review based on Diagnostic and Statistical Manual (DSM-IV-TR) criteria. Multisite, population-based data from the Autism and Developmental Disabilities Monitoring (ADDM) Network were analyzed from areas of Arizona (AZ), Georgia (GA), Maryland (MD), and South Carolina (SC). Participants were 8-year-old children (born in 1992, 1994, or 1996) in 2000, 2002, or 2004 (and children born in 1988 residing in metropolitan Atlanta in 1996) who had been evaluated for a variety of developmental concerns at education and/or health sources. RESULTS From 2000 to 2004, the identified prevalence of the ASDs per 1,000 8-year-old children showed significant increases of 38% in GA and 72% in MD and a nonsignificant increase of 26% in AZ. ASD prevalence was relatively stable in SC with a nonsignificant decrease of 17%. Males had a higher identified prevalence of ASD in all years. Increases among racial, ethnic, and cognitive functioning subgroups varied by site and surveillance year. More children were classified with an ASD by community professionals over time, except in AZ. CONCLUSIONS There was a trend toward increase in identified ASD prevalence among 8-year-old children who met the surveillance case definition in 3 of the 4 study sites from 2000 to 2004. Some of the observed increases are due to improved ascertainment; however, a true increase in ASD symptoms cannot be ruled out. These data confirm that the prevalence of ASDs is undergoing significant change in some areas of the United States and that ASDs continue to be of urgent public health concern.

Autism spectrum disorder prevalence and proximity to industrial facilities releasing arsenic, lead or mercury

Prenatal and perinatal exposures to air pollutants have been shown to adversely affect birth outcomes in offspring and may contribute to prevalence of autism spectrum disorder (ASD). For this ecologic study, we evaluated the association between ASD prevalence, at the census tract level, and proximity of tract centroids to the closest industrial facilities releasing arsenic, lead or mercury during the 1990s. We used 2000 to 2008 surveillance data from five sites of the Autism and Developmental Disabilities Monitoring (ADDM) network and 2000 census data to estimate prevalence. Multi-level negative binomial regression models were used to test associations between ASD prevalence and proximity to industrial facilities in existence from 1991 to 1999 according to the US Environmental Protection Agency Toxics Release Inventory (USEPA-TRI). Data for 2489 census tracts showed that after adjustment for demographic and socio-economic area-based characteristics, ASD prevalence was higher in census tracts located in the closest 10th percentile compared of distance to those in the furthest 50th percentile (adjusted RR=1.27, 95% CI: (1.00, 1.61), P=0.049). The findings observed in this study are suggestive of the association between urban residential proximity to industrial facilities emitting air pollutants and higher ASD prevalence.

Retention of autism spectrum diagnoses by community professionals: findings from the autism and developmental disabilities monitoring network, 2000 and 2006.

Objective: Past research is inconsistent in the stability of autism spectrum disorder (ASD) diagnoses. The authors therefore sought to examine the proportion of children identified from a population-based surveillance system that had a change in classification from ASD to non-ASD and factors associated with such changes. Methods: Children with a documented age of first ASD diagnosis noted in surveillance records by a community professional (n = 1392) were identified from the Autism and Developmental Disabilities Monitoring Network. Children were considered to have a change in classification if an ASD was excluded after the age of first recorded ASD diagnosis. Child and surveillance factors were entered into a multivariable regression model to determine factors associated with diagnostic change. Results: Only 4% of our sample had a change in classification from ASD to non-ASD noted in evaluation records. Factors associated with change in classification from ASD to non-ASD were timing of first ASD diagnosis at 30 months or younger, onset other than developmental regression, presence of specific developmental delays, and participation in a special needs classroom other than autism at 8 years of age. Conclusions: Our results found that children with ASDs are likely to retain an ASD diagnosis, which underscores the need for continued services. Children diagnosed at 30 months or younger are more likely to experience a change in classification from ASD to non-ASD than children diagnosed at 31 months or older, suggesting earlier identification of ASD symptoms may be associated with response to intervention efforts or increased likelihood for overdiagnosis.

Effect of Incorporating Adaptive Functioning Scores on the Prevalence of Intellectual Disability.

Surveillance and epidemiologic research on intellectual disability often do not incorporate adaptive functioning (AF) data. Exclusion of AF data leads to overestimation of the prevalence of intellectual disability, the extent of which is not known. In this study, the authors evaluated the effect of incorporating AF data on overall intellectual disability prevalence according to sociodemographic, economic, and severity characteristics. Between 2002 and 2006, the Metropolitan Atlanta Developmental Disabilities Surveillance Program identified 1,595 8-year-old children who met the studys intellectual disability surveillance-case definition of IQ ≤ 70. AF scores were not available for 9.2% of the case children, specifically those with mild intellectual disability and low socioeconomic backgrounds. Prevalence estimates showed few substantive changes when incorporating AF data. The authors conclude that use of IQ data alone appears to be appropriate for measuring population intellectual disability prevalence.

Autism Spectrum Disorder Among US Children (2002–2010): Socioeconomic, Racial, and Ethnic Disparities

Objectives To describe the association between indicators of socioeconomic status (SES) and the prevalence of autism spectrum disorder (ASD) in the United States during the period 2002 to 2010, when overall ASD prevalence among children more than doubled, and to determine whether SES disparities account for ongoing racial and ethnic disparities in ASD prevalence. Methods We computed ASD prevalence and 95% confidence intervals (CIs) from population-based surveillance, census, and survey data. We defined SES categories by using area-level education, income, and poverty indicators. We ascertained ASD in 13 396 of 1 308 641 8-year-old children under surveillance. Results The prevalence of ASD increased with increasing SES during each surveillance year among White, Black, and Hispanic children. The prevalence difference between high- and low-SES groups was relatively constant over time (3.9/1000 [95% CI = 3.3, 4.5] in 2002 and 4.1/1000 [95% CI = 3.6, 4.6] in the period 2006-2010). Significant racial/ethnic differences in ASD prevalence remained after stratification by SES. Conclusions A positive SES gradient in ASD prevalence according to US surveillance data prevailed between 2002 and 2010, and racial and ethnic disparities in prevalence persisted during this time among low-SES children.