˜ CORREA–VILLASENOR ET AL.
Whenever possible, MACDP also ascertains affected pregnancies that are prenatally diagnosed and terminated prior to 20 weeks of gestation. Because of incomplete as- certainment, records of prenatally diagnosed cases are an- alyzed separately.
Case subjects not included in MACDP are children with functional or metabolic disorders (e.g., cerebral palsy or phenylketonuria), hematological disorders (e.g., sickle cell disease, thalassemia, or hemophilia), minor defects (e.g., preauricular tags), and normal variants. Nevertheless, if a child has one or more major defects, then all defects, major and minor, and the presence of metabolic conditions are recorded because information on all defects can be helpful in the recognition of syndromes or patterns of multiple congenital anomalies.
Figure 1. Metropolitan Atlanta Congenital Defects Program: Study Population.
data for education and health policy decisions leading to prevention.
Over the years, MACDP has served as a model for birth defects surveillance programs in the United States and in other countries, a source of cases for epidemiologic studies, and a training ground for birth defects investigators (Khoury and Edmonds, ’92). In this paper, we present an overview of methods, accomplishments, and future plans for MACDP in celebration of its 35th anniversary.
METHODS Population Covered
The population covered by MACDP includes all births occurring to residents of five counties in Metropolitan Atlanta (Figure 1): Clayton, Cobb, DeKalb, Fulton, and Gwinnett. The metropolitan Atlanta area has grown over the past two decades and now includes over 15 counties surrounding the 5 MACDP counties. The number of yearly births and the racial and ethnic composition of the base population have also changed over the years, and one of the challenges for MACDP has been to keep up with such growth. MACDP started with about 26,000 births per year and 587 cases of birth defects in 1968. In 2000, there were approximately 50,000 live births and 1,500 cases of birth defects. The percentage of non-white births has increased over time, from about 27% in 1968 to 48% in 2000.
Congenital anomalies, congenital malformations, and birth defects are synonymous terms used to describe an abnormality of structure, or function present at birth that is fatal or can result in physical or mental disability. For practical reasons, the inclusion criteria used for case ascer- tainment by MACDP are as follows:
1. Residence of birth mother in the five-county metro- politan Atlanta area at the time of delivery;
2. Presence of serious or major structural defects that can have adverse effects on health or development;
Ascertainment made by 6 years of age; and
Gestation of 20 weeks or more.
Cases in MACDP are identified on an ongoing basis by trained abstractors who actively search newborn hospitals, pediatric hospitals, and other sources. At newborn hospi- tals, CDC abstractors review all available logs, including: obstetric logs, newborn nursery logs, neonatal intensive care unit logs, postmortem logs, surgery records, and dis- ease indices. Several conditions prompt abstractors to re- view thoroughly the medical records of infants, including any birth defect mentioned, preterm infants (37 weeks) and low birth weight infants (2500 grams), stillbirths and neonatal deaths, newborn surgical procedures, and all newborns in high-risk or special care nurseries.
At pediatric hospitals, abstractors also review comput- erized discharge indices and surgery and pathology records, if available. Any mention of a birth defect prompts abstractors to review thoroughly the medical records of infants and children.
Searches are also made through birth certificates, fetal death and death certificates obtained from the Georgia Department of Human Resources. Records of pathology reports for terminations, abortion records, autopsy records, and records of cytogenetic laboratories are also reviewed periodically.
Use of multiple sources for case ascertainment is more resource intensive and requires more time to prepare a database for analysis compared to programs that use more limited sources. However, use of multiple-source case as- certainment in MACDP has ensured a more complete case recording, more precise and accurate diagnoses, availabil- ity of maternal and infant data, and relative ease for re- searchers to conduct follow-up studies of children with birth defects.
A special abstraction form is used by abstractors to collect information on infants and children who meet the MACDP case definition. Data collected and coded include:
1. Identifying information on each infant, mother, and father that allows for comparison and linkage of multiple sources of case ascertainment;
2. Demographic information, including sex, maternal age, race and, ethnicity;
Diagnostic information on each type of birth defect;
Pregnancy information from prenatal and obstetric
records, including plurality, gestational age, date of last
Birth Defects Research (Part A) 67:617–624 (2003)