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Introduction
Since 1968, The Centers for Disease Control and Prevention (CDC) has
conducted surveillance of birth defects (i.e., structural malformations
and genetic diseases) in the five-county metropolitan Atlanta area.
However, those birth defects that are evident at birth (e.g., cleft palate
and spina bifida) represent only part of a spectrum of developmental
problems that appear during childhood. Other conditions (e.g., mental
retardation, autism, and cerebral palsy) usually are manifested after
infancy and may be sufficiently severe to require specialized medical and
education services for many years. Such conditions are referred to as
developmental disabilities.
To address the problem of developmental disabilities among children,
CDC, the former Division of Birth Defects and Developmental Disabilities,
which was funded by the Agency
for Toxic Substances and Disease Registry (ATSDR), and the Georgia
Department of Human Resources, initiated the Metropolitan
Atlanta Developmental Disabilities Study (MADDS) in 1984. For this
study, which was conducted in Atlanta during 1984-1990, investigators
devised methods for determining the prevalence of mental retardation,
cerebral palsy, legal blindness, hearing loss, and epilepsy among
children 10 years of age. Children who had these conditions were
identified by searching record systems of sources that were likely to
contain information relating to the evaluation or treatment of children
with developmental disabilities (e.g., schools, hospitals, and state
programs for persons who have developmental disabilities). The majority of
the children were identified through special education departments within
the Atlanta area public school systems. The success of this study prompted
CDC to establish the Metropolitan Atlanta Developmental Disabilities
Surveillance Program (MADDSP) in 1991, an ongoing system for
monitoring the occurrence of selected developmental disabilities. MADDSP
is located at CDC in the National Center on Birth Defects and
Developmental Disabilities.
The two principal objectives of MADDSP are to a)
provide regular and systematic monitoring of prevalence rates of selected
developmental disabilities according to various demographic
characteristics of children and their mothers and b) provide a framework
for initiating special studies of children who have the selected
developmental disabilities by establishing a population-based case series
of such children.
Methods
MADDSP was established to ascertain all children who have one or more
of four developmental disabilities -- mental retardation, cerebral palsy,
hearing loss, and vision impairment -- in the five-county (i.e.,
Clayton, Cobb, Dekalb, Fulton, and Gwinnett) metropolitan Atlanta area.
Autism spectrum disorders was
added as a fifth disability beginning in the 1996 study year. In 1996, the
study area had a population of 33,309 8-year-olds and 289,456 children
3-10 years of age. This area has an active
birth defects surveillance program -- the Metropolitan Atlanta Congenital
Defects Program, which is operated by CDC. Consequently, additional
medical data can be obtained by linking the children identified through
MADDSP to the birth defects registry.
The ascertainment methodology of MADDSP relies on the consequences of
Part B of Public Law 94-142 "as amended", the Individuals with
Disabilities Education Act (IDEA), which mandates that the public schools
provide a free and appropriate education for all disabled children between
the ages of 3 and 21 years. As a result, most children eligible for MADDSP
are either enrolled in special education programs at nine public school
systems serving the study area or enrolled in other Georgia Department of
Education programs for children who have developmental disabilities (e.g.,
state schools for children who are hearing or vision impaired and regional
psychoeducational centers). Additional
sources used to identify children include Georgia Department of Human
Resources facilities for children with a developmental disability, area
pediatric hospitals and the clinics associated with these facilities,
comprehensive diagnostic and evaluation centers for individuals with
developmental disabilities, as well as a number of private physicians and
clinicians who provide diagnostic services for children with developmental
disabilities.
Source records (e.g., medical and school records) are reviewed annually
for children who are potentially eligible for inclusion in the
surveillance program.
In the 1991-1994 study years,
children aged 3- to 10-years were included in MADDSP. Starting in
the 1996 study year, we began to focus on a narrower age range in order to
make the surveillance program more timely.
Case definition
For the 2000 study year, a case
child in MADDSP is defined as a child:
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Who is 8 years old any time during the study year of
interest;
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Whose parent(s) or legal guardian(s) reside in the five-county
metropolitan Atlanta area at some time during the study year of
interest; and
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Who has one or more of the five developmental disabilities.
Developmental Disabilities Definitions
Autism Spectrum Disorders
Autism Spectrum Disorders (ASD) are defined as a constellation of behaviors indicating social, communicative, and behavioral impairment or abnormalities. The essential features of ASD are (a) impaired reciprocal social interactions, (b) delayed or unusual communication styles, and (c) restricted or repetitive behavior patterns.
A child is included as a confirmed case of ASD if he or she displays behaviors (as described by a qualified professional) consistent with the Diagnostic and Statistical Manual of Mental Disorders - Fourth Edition (DSM-IV) diagnostic criteria for Autistic Disorder, Pervasive Developmental Disorder-Not Otherwise Specified (including Atypical Autism), or
Asperger's Disorder. A qualified professional is defined as an educational, psychological or medical professional with specialized training in the observation of children with developmental disabilities (e.g., special education teacher, clinical / developmental / school psychologist, speech/language pathologist, learning specialist, social worker, developmental pediatrician, child psychiatrist, pediatric neurologist).
Behavioral descriptions are reviewed by autism experts using a coding
scheme based on DSM-IV criteria to determine autism case status.
Cerebral Palsy
Cerebral palsy is defined as a group of non-progressive, but often changing, motor impairment syndromes secondary to lesions or anomalies of the brain arising at any time during brain development. Children with postnatally acquired cerebral palsy are included. The impairment of motor function may result in paresis, involuntary movement, or incoordination. It does not include motor disorders that are transient, that result from progressive disease of the brain, or that are due to spinal cord abnormalities/injuries.
Children are included as confirmed cases of cerebral palsy if they have been (a) diagnosed as having cerebral palsy by a qualified physician or (b) identified by other qualified professionals as having this disability on the basis of physical findings noted in source records. A qualified professional is defined as a physician, physical therapist, occupational therapist, nurse practitioner, or physician's assistant who specializes in developmental disabilities, neurology, orthopedics or pediatrics. A determination is made by medical staff of the Developmental Disabilities
Program that the physical findings are consistent with a diagnosis of cerebral palsy.
Hearing Loss
Hearing loss is defined as a measured, bilateral, pure-tone hearing loss at frequencies of 500, 1000, and 2000 hertz averaging 40 decibels (dB) or more, unaided, in the better ear. In the absence of a measured, bilateral hearing loss, children meet the case definition if their source records include a description, by a licensed or certified audiologist or qualified physician, of a hearing loss of 40 dB or more in the better ear (e.g., profound sensorineural hearing loss). Severity is defined on the basis of the following hearing
loss levels (measured in the better ear): moderate (a hearing loss of 40-64 dB), severe (a hearing loss of 65-84 dB), and profound (a hearing loss of >=85 dB).
Mental retardation /Intellectual Disability
Mental retardation is defined as a condition marked by an intelligence quotient (IQ) of <=70 on the most recently administered psychometric test. In the absence of an IQ score, a written statement by a psychometrist that a child's intellectual functioning falls within the range for mental retardation is acceptable. The severity of mental retardation is defined according to the following International Classification of Disease, Ninth Edition, Clinical Modification (ICD-9-CM) categories: mild (an IQ of 50-70), moderate (an IQ of 35-49), severe (an IQ of 20-34), and profound (an IQ of <20).
Vision Impairment
Vision impairment is defined as a measured visual acuity of 20/70 or worse, with correction, in the better eye. In the absence of a measured visual acuity, a child is considered a case if a source record includes (a) a functional description, by a qualified physician or vision professional, of visual acuity of 20/70 or worse (e.g., light perception only) or (b) a statement by a qualified physician or vision professional that the child has low vision or blindness. Severity of visual impairment is defined using the WHO categories low vision (20/70 - 20/400) and blindness (worse than 20/400) or the U.S.A. categories of low vision (20/70 to better than 20/200) and legal blindness (20/200 or worse).
Prevalence
Prevalence of selected developmental disabilities among children 8 years
of age, Metropolitan Atlanta Developmental Disabilities Surveillance
Program, 2000 Surveillance Year per 1,000 children:
Publications
National Center on Birth Defects and Developmental Disabilities (NCBDDD) staff have written scientific papers
using information from MADDSP. These papers look at such topics as how common
autism spectrum disorders are and what causes hearing loss in children. You can see a list of these papers (starting in 1990) by using the keyword search on the NCBDDD
publications Web page. Choose "MADDSP (Metropolitan Atlanta
Developmental Disabilities Surveillance Program)" in the keyword box on the search page.
You can choose whether you want the list to be sorted by author or by date.
You can also choose to have the list appear with or without graphics.
Click on the Submit button. You will see a list of papers that have
information from MADDSP. The list will include the complete reference for each paper and a link to an abstract of the paper or to the full
text, when available. [Go
to NCBDDD publications keyword search page]
Return to Previous Page
Date: October 29, 2004
Content source: National Center on Birth Defects and Developmental
Disabilities
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