ADDM Network Methods
The Autism and Developmental Disabilities Monitoring (ADDM) Network is the only collaborative network to track the number and characteristics of children with ASD in multiple communities in the United States. Since the launch of the ADDM Network in 2000, CDC has funded 16 sites in areas of Alabama, Arizona, Arkansas, Colorado, Florida, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Pennsylvania, South Carolina, Tennessee, Utah, West Virginia, and Wisconsin. CDC also operates an additional ADDM site in Georgia. The ADDM Network tracks more than 300,000 8-year-old children.
The ADDM Network’s goals are to
- Obtain as complete a count as possible of the number of children with ASD in each ADDM Network area and identify changes in that count over time;
- Provide information on the characteristics of children with ASD, including sex, race/ethnicity, co-occurring intellectual ability, and age of evaluation and diagnosis;
- Determine whether ASD is more common in some groups of children (for example, among boys versus girls) than among others, and if those differences are changing over time; and
- Understand the impact of ASD and related conditions upon children, families, and communities in the United States.
How does ADDM develop estimates?
The ADDM Network estimates the number of children with ASD using a record review method. This review includes both children who have an ASD diagnosis and children who haven’t received a diagnosis but do have documented behaviors that are consistent with ASD.
What are the different ways of estimating the number of children with ASD?
There are several different ways to estimate the number of children with ASD, and each method has its advantages and disadvantages.
|Method||What Is It?||Advantages and Disadvantages|
|Population-based screening and evaluation||Screening and evaluating a sample of all children in a population, within a defined age group.||Can provide high accuracy, but can be costly and time-consuming, and might produce skewed results based on who agrees to participate.|
|National surveys||Collecting information via standardized instruments, such as telephone interviews or self-completed questionnaires.||Is representative of national characteristics, but might reflect bias based on who participates and how ASD is defined and reported.|
|Registries||Collecting information on children and families who voluntarily include themselves on a list of people affected by ASD.||Relatively low cost, but time-consuming and includes only individuals with a clear diagnosis and families who know about the registry and are willing to be on the list.|
|Administrative data||Looking at codes for services in records from Medicaid and agencies, such as the U.S. Department of Education.||Relatively low cost, but can underestimate prevalence because not all children with ASD are receiving services for ASD or have been diagnosed with ASD.|
|Systematic record review (ADDM Network’s Method)||Reviewing health and special education records to identify children with ASD behaviors.||Relatively cost-effective and uses multiple data sources to identify children who might not have a clear ASD diagnosis already, but relies on the quality and quantity of information in records and,|
What are the advantages of the ADDM Network method?
There are several major advantages to using the ADDM Network method for tracking the number and characteristics of children with ASD. For example, the ADDM Network
- Is the largest, ongoing ASD tracking system in the United States;
- Uses a method that is population-based, which means we try to identify all the children with ASD from the entire population of children in a defined geographic area (or multiple geographic areas);
- Can track changes over time within different communities and within different groups (such as racial/ethnic groups);
- Collects information from multiple sources in the community where children are served, including schools and local clinics; and
- Uses expert reviewers to make a decision about whether a child has ASD, based on review of symptoms documented in multiple records. This means children with ASD are included in the total count even if they did not have an ASD diagnosis in their records.
What else is the ADDM Network doing?
In 2010 and 2012, the Early ADDM Network, a subset of the ADDM Network, tracked ASD among 4-year-olds in areas of Arizona, Missouri, New Jersey, Utah, and Wisconsin. Beginning with the 2014 tracking year, the Early ADDM Network tracked ASD among 4-year-olds in areas of Arizona, Colorado, Missouri, New Jersey, North Carolina, and Wisconsin. Tracking among 4-year-old children increases our understanding of the characteristics and early identification of younger children with ASD.
Some ADDM Network sites also track the number and characteristics of children with other developmental disabilities including cerebral palsy and intellectual disability.