Down syndrome (DS) is a serious birth defect that occurs in approximately 1out of every 800 live births in the United States. DS is associated with mental retardation, congenital heart defects, dysmorphic facial features, hand anomalies, and defects of the gastrointestinal tract, the immune system, and the endocrine system. People with DS are also at an increased risk of leukemia and dementia. Survival with DS has improved over the years, with the median age at death increasing from 25 years of age in 1983 to 49 years of age in 1997. The DS phenotype is caused by trisomy of chromosome 21, which is the presence of additional chromosome 21 materials in addition to the normal set of chromosomes. The most common form of DS occurs when there is a complete extra copy of chromosome 21 (non-disjunction, 92% of US cases). The second most common form of DS occurs when part or all of chromosome 21 is translocated to another chromosome, usually chromosome 14 (3-4% of U.S. cases). Individuals with the first two forms of DS are typically indistinguishable by phenotype. Mosaic Down syndrome, the least common form, occurs when a proportion of the cells in the body have the normal number of chromosomes, and the remaining cells have trisomy 21 (2-3% of U.S. cases). Individuals with mosaic DS can have milder physical features associated with the birth defect than children with non-disjunction or translocation. Risk factors for DS include maternal age, history of a previous pregnancy affected by DS, and the translocation of parental chromosome 21. Recent birth prevalence estimates for DS have been reported by at least 35 states in the U.S. The birth prevalence from 1997 through 2002 ranged from 10.63 per 10,000 live births in New York to 18.12 per 10,000 live births in Colorado. Spina bifida (SB) is a common birth defect that develops within the first 28 days after conception and results from the improper closure of the neural tube. The more severe cases of SB are associated with physical, mental, and psychological difficulties. Early complications include problems with walking and coordination, urinary and bowel incontinence, and limb numbness and paralysis. Long-term complications and secondary conditions include scoliosis, seizures, shunt complications, urinary tract infections, latex allergies, skin ulcerations, obesity, a decreased growth rate, learning disabilities, and emotional problems. Survival to age 1 among infants born with SB in Atlanta has improved from 85.4% in 1979-1983 to 95.5% in 2000-2002. The prevalence of SB has been decreasing in the United States and other regions of the world. This decline in SB prevalence at birth could be due to fortification of foods with folic acid, increased multivitamin use during the periconceptional period of pregnancy, and an increased prenatal detection and termination of SB pregnancies. In some areas of the United States, approximately 20% to 30% of pregnancies affected by neural tube defects are electively terminated. In 2000, the birth prevalence of SB without electively terminated. In 2000, the birth prevalence of SB without anencephaly was approximately 2 out of every 10,000 live births in the U.S., and survival has improved through the years. Recent birth prevalence estimates for SB have been reported by at least 35 states in the U.S. The birth prevalence from 1997 through 2002 ranged from 1.85 per 10,000 live births in New Jersey to 6.03 per 10,000 live births in Iowa. The primary purpose of this study is to provide prevalence estimates (by state and metro region) for Down syndrome (DS) and spina bifida (SB) among children and adolescents and to determine the survival probabilities and predictors of survival for these infants. The National Center on Birth Defects and Developmental Disabilities recently developed a methodology to estimate the prevalence of SB among children and adolescents in Atlanta using data from the Metropolitan Atlanta Congenital Defects Program (MACDP) and from the U.S. Census. Using regional birth defects surveillance data, these methods will be replicated in this study to estimate prevalence of children and adolescents with SB and DS (separately) in metropolitan Atlanta, Arkansas, California, Colorado, Hawaii, Iowa, New York, New Jersey, North Carolina, Oklahoma, and Utah. Case infants with DS or SB identified in each region will be divided into birth cohorts and brought forward in time to determine their survival in future time periods. Vital status will be ascertained using state vital records, case records from the state birth defects registries, and by linking to the National Death Index. Prevalence estimates will be calculated by age, sex, race, heart defect (DS cases only) and lesion site (SB cases only). For more recent years (i.e. 2000'2002), prevalence ratios and 95% confidence intervals will be calculated. Survival analysis will include the estimation of survival probabilities by age and birth cohort, as well as overall survival by race, sex, birth weight, gestational age, plurality, apgar score, and pediatric hospital admission (when these variables are available from a given registry). The predictors of survival will also be examined, and will include the previously described variables as well as mother's and father's education, and mother's and father's age. The survival analysis will be conducted using methods similar to those previously used by the National Center on Birth Defects and Developmental Disabilities (NCBDDD). All state birth defects registries were reviewed to determine: (1) if they had sufficient years of data; (2) surveillance methods that could provide necessary level case ascertainment; and (3) administrative support to complete the work. Birth defect surveillance programs were not considered if they could not provide case ascertainment through population-based active surveillance process or through a passive system with confirmed diagnoses or if they could not provide down syndrome and spina bifida case data from at least 1995 through 2002. The following state birth defect surveillance programs meet all requirements necessary to contribute to a study that will investigate the prevalence of down syndrome in the population through adolescence: Iowa, Oklahoma, New York, Colorado, North Carolina, Utah, Texas, Arkansas, and California. Thus, CDC intends to issue multiple awards on the basis of sole source to the following organizations, which were found to have the required surveillance methods to supply mortality data with sufficient years of follow up to contribute to this study: (1) The University of Iowa, 200 Hawkins Dr., Iowa City, IA 52242; (2) Oklahoma State Department of Health, Oklahoma City, OK 73117; (3) Health Research, Inc., New York State (4) Department of Health, One University Place, Resselaer, NY 12144; (5) Colorado Department of Health and Environment, 4300 Cherry Creek Dr., Denver, CO 80246; (5) State Center for Health Statistics; Division of Publish Health, North Carolina Department of Health and Human Services; (7) Utah State Department of Health, Salt Lace City, UT 84114-4699; (8)Department of State Health Services, 1100 W. 49th St., Austin, TX 78756; (9)Arkansas Children's Hospital Research Institute,1120 Marshall St., Little Rock, AR 72202; March of Dimes Birth Defects Foundation, 1615 Fifth Street, First Floor, Davis, CA 95616.
