The
To assess potential effects of the
Cross-sectional, population-based ASD surveillance based on clinician review of coded behaviors documented in children’s medical and educational evaluations from 14 geographically defined areas in the United States participating in the Autism and Developmental Disabilities Monitoring (ADDM) Network in 2006 and 2008. This study included 8-year-old children living in ADDM Network study areas in 2006 or 2008, including 644 883 children under surveillance, of whom 6577 met surveillance ASD case status based on the
Proportion of children meeting ADDM Network ASD criteria based on the
Among the 6577 children classified by the ADDM Network as having ASD based on the
Autism spectrum disorder prevalence estimates will likely be lower under
Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders characterized by impairments in social interaction and communication, as well as repetitive behaviors and restricted interests. The American Psychiatric Association first described
Population reports from developed countries show consistent, secular increases in ASD prevalence since the mid-1990s.
Some experts suggest the
We used data from the Autism and Developmental Disabilities Monitoring (ADDM) Network, an active, population-based surveillance system that implements a multisite, multiple-source, health and education record review methodology. The ADDM Network monitored ASD prevalence among 644 883 8-year-old children who resided in 11 US surveillance sites during the 2006 surveillance year and 14 US sites during 2008.
Details of the ADDM Network have been described previously.
The
The ADDM Network ASD case definition was based on the
The
We operationalized the
For the 2006 and 2008 surveillance years, ADDM Network clinician reviewers determined 6577 children met ASD criteria based on the
To calculate the potential impact on prevalence, we applied
We performed χ2 tests to assess differences in proportions, and we calculated 95% CIs using the binomial exact method. All analyses were performed with the R Statistical Computing Package version 2.15.3 (R Foundation for Statistical Computing). Plots were created with ggplot2.
Among the 6577 children who met the ADDM Network ASD case definition based on the
The proportion of children who met
We observed a substantial association between the proportion meeting
When ASD prevalence estimates are adjusted to include only children meeting
These results suggest that fewer children would have been classified as having ASD using the
The potential reduction in ASD prevalence under the
An advantage of the population-based design was that it is representative of all children in defined populations who meet ASD criteria and are evaluated in typical community settings rather than selected samples attending a particular clinic or enrolled in specific research projects. Another important strength of this study was that we considered children who may meet
Previous introductions of new criteria for ASD suggest that the process by which professionals become trained in and familiar with the new diagnostic or eligibility criteria is gradual.
Children identified as having ASD by a community professional were more likely to meet
A limitation of this study was its reliance on symptoms documented in records by professionals in the community during a time when the
Some children meeting PDD criteria under the
The results of this population-based study suggest ASD prevalence estimates may be lower under the
The bar graph shows the proportion of children who met
The graph shows a comparison of previously reported Autism and Developmental Disabilities Monitoring (ADDM) Network autism spectrum disorder (ASD) prevalence estimates (2000–2008 surveillance years) to prevalence using
Operational Approaches for
| Persistent deficits in social communication and social interaction across contexts, not accounted for by general developmental delays, and manifest by all 3 of the following: | ||
| Deficits in social-emotional reciprocity; ranges from abnormal social approach and failure of normal back and forth conversation through reduced sharing of interests, emotions, and affect and response to total lack of initiation of social interaction | 99.1 | |
| Deficits in nonverbal communicative behaviors used for social interaction; ranges from poorly integrated verbal and nonverbal communication through abnormalities in eye contact and body language or deficits in understanding and use of nonverbal communication to total lack of facial expression or gestures | 86.8 | |
| Deficits in developing and maintaining relationships appropriate to developmental level (beyond those with caregivers); ranges from difficulties adjusting behavior to suit different social contexts through difficulties in sharing imaginative play and in making friends to an apparent absence of interest in people | 97.5 | |
| Restricted, repetitive patterns of behavior, interests, or activities as manifested by at least 2 of the following: | ||
| Stereotyped or repetitive speech, motor movements, or use of objects (eg, simple motor stereotypies, echolalia, repetitive use of objects, or idiosyncratic phrases) | 96.5 | |
| Excessive adherence to routines, ritualized patterns of verbal or nonverbal behavior, or excessive resistance to change (eg, motoric rituals, insistence on same route or food, repetitive questioning, or extreme distress at small changes) | 85.7 | |
| Highly restricted, fixated interests that are abnormal in intensity or focus (eg, strong attachment to or preoccupation with unusual objects, excessively circumscribed or perseverative interests) | 62.8 | |
| Hyper- or hyporeactivity to sensory input or unusual interest in sensory aspects of environment (eg, apparent indifference to pain/heat/cold, adverse response to specific sounds or textures, excessive smelling or touching of objects, fascination with lights or spinning objects) | 80.8 | |
| Symptoms must be present in early childhood (but may not become fully manifest until social demands exceed limited capacities) | Documented impairments by age 8 y | 100.0 |
| Symptoms together limit and impair everyday functioning | Referred for a developmental evaluation | 100.0 |
| ADDM Network ASD case children who met | 81.2 | |
| ADDM Network ASD case children meeting, or within 1 criterion of meeting, | ||
| Only required 2 of 3 social communication criteria | 93.6 | |
| Only required 1 of 4 repetitive/restricted criteria | 83.7 | |
| Required 1 fewer criterion from either social communication or repetitive/restricted domains (met 1 or 2 of the above) | 96.1 |
Abbreviations: ADDM, Autism and Developmental Disabilities Monitoring; ASD, autism spectrum disorder.
Using ADDM Network clinician reviewers’ coding of the
Characteristics of Children Who Met
| Characteristic | ADDM Network ASD Case Children, No. | ||
|---|---|---|---|
| % | |||
| Total | 6577 | 81.2 | |
| Surveillance, y | |||
| 2006 | 2757 | 78.5 | <.001 |
| 2008 | 3820 | 83.1 | |
| Sex | |||
| Boy | 5452 | 81.4 | .29 |
| Girl | 1125 | 80.0 | |
| Race/ethnicity | |||
| Black, non-Hispanic | 1482 | 82.2 | .001 |
| White, non-Hispanic | 3674 | 81.6 | |
| Asian/Pacific Islander | 192 | 88.0 | |
| Hispanic | 803 | 78.1 | |
| Other, multiracial, and unknown | 426 | 76.5 | |
| Intellectual disability | |||
| IQ≤70 | 1879 | 86.6 | <.001 |
| IQ>70 | 3042 | 82.5 | |
| IQ unknown | 1656 | 72.5 | |
| History of developmental regression | |||
| Yes | 1365 | 89.4 | <.001 |
| No/unknown | 5212 | 79.0 | |
| Identified as having autism by a professional in the community | |||
| Yes | 5007 | 84.8 | <.001 |
| No/unknown | 1570 | 69.7 | |
| ADDM Network site | |||
| Alabama | 386 | 74.9 | <.001 |
| Arkansas | 52 | 88.5 | |
| Arizona | 1011 | 81.1 | |
| Colorado | 145 | 88.3 | |
| Florida | 327 | 68.8 | |
| Georgia | 1075 | 85.5 | |
| Maryland | 579 | 69.1 | |
| Missouri | 678 | 83.3 | |
| New Jersey | 145 | 88.3 | |
| North Carolina | 755 | 88.2 | |
| Pennsylvania | 395 | 80.0 | |
| South Carolina | 460 | 82.2 | |
| Utah | 45 | 95.6 | |
| Wisconsin | 524 | 79.4 | |
Abbreviations: ADDM, Autism and Developmental Disabilities Monitoring; ASD, autism spectrum disorder; IQ, intelligence quotient.
Abstracted record contained a diagnosis of autistic disorder, pervasive developmental disorder not otherwise specified, Asperger disorder, or autism from a community professional, or child received special education services under autism eligibility during the surveillance year.
Summary of Previous Studies Comparing
| Source (Country) | Study Description | Sample Size (With ASD) | Description Sample With Previous ASD Diagnosis | Proportion Who Met | |||
|---|---|---|---|---|---|---|---|
| Overall, % | By | By IQ | If Criteria Were Relaxed | ||||
| Mattila et al, | Retrospective review: population screening in schools with ASSQ followed by diagnostic phase using | 26 | 8-year-olds with IQ≥50 who completed diagnostic phase (15 autism, 11 Asperger disorder) | 46 | 0% with Asperger disorder | 100% with IQ 50–69; | 96% after 5 modifications (including requiring 2 of 3 A criteria) |
| Taheri and Perry, | Retrospective review: several studies of behavioral intervention containing a | 131 | Children aged 2 to 12 y (93 autistic disorder, 36 PDD-NOS, and 2 not previously diagnosed) | 63 | 81% with autistic disorder; | 90% with IQ<40; | 73% when required 1 of 4 B criteria; |
| McPartland et al, | Reanalysis of | 657 | Children and adults aged 1 to 43 y (450 autistic disorder, 48 Asperger disorder, 159 PDD-NOS) | 61 | 76% with autistic disorder; | 70% with IQ<70; | 75% when required 2 of 3 A criteria |
| Gibbs et al, | Clinical evaluation of children referred for an autism diagnostic assessment using the ADOS and ADI-R | 111 | Children aged 2–16 y (59 autistic disorder, 18 Asperger disorder, 34 PDD-NOS) | 77 | 90% with autistic disorder; | Noted that “at least some” more children would have met if required 1 of 4 B criteria | |
| Matson et al, | Retrospective clinician review of birth-3 program measures including the BISCUIT Part 1, M-CHAT, and BDI-2 | 773 | Toddlers aged 17–36 mo (breakdown by ASD subtype not stated) | 52 | 66% when required 2 of 3 A criteria; | ||
| Matson et al, | Reanalysis of | 156 | Adults aged 18–88 y with intellectual disability (breakdown by ASD subtype not stated) | 63 | Entire sample had intellectual disability | ||
| Worley and Matson, | Reanalysis of | 180 | Children aged 3–16 y (breakdown by ASD subtype not stated) | 67 | |||
| Frazier et al, | Statistical analysis of symptom data using the SRS and SCQ as obtained from IAN Registry | 6426 | Youth aged 2–18 y (breakdown by ASD subtype not stated) | 81 | 93% when required 1 fewer criterion from either A or B | ||
| Huerta et al, | Retrospective review: 3 sources of patient and participant assessments using the ADI-R and ADOS | 4453 | Children aged 2–17 y, 11 mo (3221 autistic disorder, 971 PDD-NOS, 261 Asperger disorder) | 91 | 89%–93% with PDD-NOS and Asperger disorder (combined group); | 86%–91% with IQ>70; | |
| Mazefsky et al, | Mapped ADOS and ADI-R items onto | 498 | Participants aged 5–61 y (breakdown by ASD subtype not stated) | 93 | Sample mean IQ = 105, range 69–141 | ||
| Mayes et al, | Evaluation (parent interview; review of records; test scores; psychological testing) in psychiatric and developmental pediatrics samples | 93 | Children aged 1–16 y (29 autism with IQ≥80, 34 autism with IQ<80, 30 PDD-NOS) | 82 | 47% with PDD-NOS | 100.0% with IQ≥80; | 91% when required 1 fewer criterion |
| Wilson et al, | Mapped | 80 | Adults aged 18–65 y (Asperger disorder or autistic disorder, breakdown not given) | 76 | 85% when required 2 of 3 A criteria; | ||
| Current study (US) | Population-based surveillance using retrospective record review | 6577 | 8-year-old children who met ADDM Network case definition for autistic disorder, Asperger disorder, or PDD-NOS | 81 | Children who met more | 87% with IQ≤70; | 96% when required 1 fewer criterion from either A or B |
Abbreviations: ADDM, Autism and Developmental Disabilities Monitoring; ADI-R, Autism Diagnostic Interview–Revised; ADOS, Autism Diagnostic Observation Schedule; ASD, autism spectrum disorder; ASSQ, Autism Spectrum Screening Questionnaire; BDI, Battelle Developmental Inventory; BISCUIT, Baby and Infant Screen for Children with Autism Traits; IAN, Interactive Autism Network;
Used an older version (2010) of the
After adjusting the sample to account for
81% of the IAN Registry youth who had a previous ASD diagnosis.