Developmental Disabilities Prevalence Rates

Prevalence of developmental disability estimates for children aged 3 to 10 years for 1991 through 1994 have been reported Metropolitan Atlanta Developmental Disabilities Surveillance Program or MADDSP uses active surveillance methods to ascertain cases of the five select disabilities in the five-county metropolitan areas.

The early developmental disabilities surveillance data indicated that prevalence rates were stable by age 8 years because, by this age, the majority of children with a developmental disability will have been participating in a special education program, and will have been identified by non-education providers. Mental retardation is defined as a disabled condition marked by an intelligence quotient or IQ of less than 70 on the most recently administered psychometric test. In the complete absence of an IQ score and in the context of testing, a written statement by a psychometrist that the intellectual functioning of a child is within the range for severe or profound mental retardation is acceptable.

Cerebral palsy is a disabled condition that defined as a group of non-progressive, but frequently changing, motor impairment syndromes secondary to lesions or anomalies of the brain arising at any time during mental growth and development. The impairment of motor function might result in involuntary movement, paresis, or in-coordination. Children who acquired cerebral palsy after birth are eligible to be patients in MADDSP, but infants with motor disorders that are transient, resulting from progressive disease of the brain or from spinal cord abnormalities or injuries, are not considered cerebral palsy cases for MADDSP.

The confirmed cases of cerebral palsy include children whose developmental conditions are diagnosed as cerebral palsy by a qualified physician or children who are 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, nurse practitioner, occupational therapist, physical therapist, or physician's assistant. Strength of mind is made by a developmental pediatrician affiliated with MADDSP that the physical findings are consistent with a diagnosis of cerebral palsy. Generally developmental pediatrician follows a set of rules for determining case status for cerebral palsy which are actually based on their clinical knowledge of the disability.

Hearing loss is a mechanical disorder that can be defined as a measured, bilateral, pure-tone hearing loss at frequencies of 500, 1,000, and 2,000 hertz averaging greater than 40 decibels (dB), unaided, in the better ear. In the deficiency of a measured, bilateral hearing loss, the conditions of the children met the case definition if their source records include a description, by a qualified physician of hearing loss or a licensed or certified audiologist of greater than 40 dB in the better ear. Severity of this disability is defined based on the hearing impairment levels, moderate, severe and profound hearing disability. Vision impairment is a kind of disability that can be defined as a measured visual acuity of 20/70 or worse, with correction, in the better eye. A child is considered a patient in the absence of a measured visual acuity, if a source record includes a functional description, by a qualified physician or vision professional, of visual acuity of 20/70 or worse or a statement by a qualified physician or vision professional that the child has low vision or blindness. The prevalence of disability estimates were calculated for each of the disabilities overall and by race, sex, and severity of the disability.