Georgia epidemiology report, Vol. 13, no. 8 (Aug. 1997)

Georgia

Epidemiology

Report

The Georgia Epidemiology Report is a publication of the Epidemiology Section of the Epidemiology and Prevention Branch, Division of Public Health, Department of Human Resources

August 1997

Volume 13 Number 8

Birth Defects Surveillance:
Metropolitan Atlanta

Centers for Disease Control and Prevention

http://www.ph.dhr.state.ga.us
Division Of Public Health
Patrick J. Meehan, MD - Director
Epidemiology and Prevention Branch State Epidemiologist Kathleen E Toomey, MD, MPH.- Director
Epidemiology Section Paul A Blake, MD, MPH-Chief
Notifiable Diseases
Jeffrey D Berschling, MPH; Cherie L. Drenzek, DVM, MS; Katherine Gibbs-McCombs, MPH; Karen R Horvat, MPH; Amri B Johnson, MPH; Jane E Koehler, DVM, MPH; Preeti Pathela, MPH
Chronic Disease
Nancy E Stroup, PhD-Program Manager Patricia M Fox, MPH; A Rana Bayakly, MPH; Edward E Pledger, MPA
Tuberculosis
Rose Marie Sales, MD, MPH -Program Manager Naomi Bock, MD, MS
HIV/AIDS/Sexually Transmitted Diseases
John F Beltrami, MD, MPH-Acting Program Manager Mary Lynn Gaffield, MPH.; Andrew Margolis, MPH
Perinatal Epidemiology
James W Buehler, MD-Program Manager Mary D Brantley, MPH; Paul C Gangarosa, MPH; Leslie E Lipscomb, MPH; Mary P Mathis, PhD, MPH
Preventive Medicine Resident
Scott E Kellerman, MD; Alexander K Rowe, MD
EIS Officer
Michael S Friedman, MD
Georgia Epidemiology Report Editorial Board
Editorial Executive Committee Paul A. Blake, M.D., M.P.H.- Editor Kathleen E. Toomey, M.D., M.P.H. Mary D. Brantley, M.P.H. Jeffrey D. Berschling, M.P.H.
Mailing List Edward E. Pledger, M.P.A.

Birth defects are notifiable conditions under special request in Georgia.
Birth defects are the leading cause of infant mortality in the United States. However, most birth defects are of unknown cause. The Centers for Disease Control and Prevention (CDC) and the Georgia Mental Health Institute created the Metropolitan Atlanta Congenital Defects Program (MACDP) in 1967. The MACDP was originally founded in the wake of, and partially as a consequence of, the thalidomide disaster in Europe and Canada. The program's objectives were:
1. To monitor, regularly and systematically, the births of malformed infants for changes in incidence or other unusual patterns suggesting preventable causes.
2. To develop a case registry for use in epidemiologic and genetic studies.
Now, 30 years later, even though the MACDP has not detected any potent new teratogens, the program still proves its usefulness in many ways.
The population under surveillance consists of all live-born and stillborn infants born to mothers living in the metropolitan Atlanta area. The MACDP defines the metropolitan Atlanta area as Clayton, Cobb, DeKalb, Fulton, and Gwinnett counties, which together cover 1,724 square miles. In 1993, the metropolitan Atlanta area had an estimated population of 2,334,000 and 39,088 resident live births. Among all resident liveborn infants, 16,586 (42.4%) were black, and 276 (0.7%) were born outside of a hospital.
For an infant to meet the current MACDP case definition, all of the following must be true:
1. The mother's residence at the time of birth must be in the five-county metropolitan area. Residence is determined by her hospital records or, if these records are in question, by vital records. The birth need not occur in the five counties.
2. The child must have a major structural or genetic birth defect. Major defects are those that can adversely affect a child's health and development. Children that have only minor defects (i.e., those that pose no significant health or social burdens) are excluded.

Epidemiology Section, Epidemiology & Prevention Branch, Two Peachtree St., N.W., Atlanta, GA 30303-3186

Phone: (404) 657-2588

FAX: (404) 657-2586

3. The defect must be diagnosed before the child's sixth birthday.
4. The defect's signs must be recognized within the first year of the child's life.
5. The infant or fetus must have a gestational age of at least 20 weeks or a birth weight of at least 500 grams.
Cases are ascertained from four major sources. The most important source is the records at the 18 hospitals with obstetric facilities serving the metropolitan Atlanta area. At these hospitals, abstracters systematically review logs from nurseries, the neonatal intensive care unit (NICU), the labor and delivery unit, the pediatric unit, and the pathology department (autopsies), as well as other records. The abstractors also review disease indices periodically. The frequency of MACDP's visits to each hospital depends on the number of births per year. For example, MACDP personnel visit a hospital with 10,000 births per year three times a week and visit smaller community hospitals (with less than 1,000 births per year) only once a month. During these visits, they complete reproductive outcomes case records (ROCRs) on all infants/fetuses meeting the case definition.

Spina Bifida Declining One good example of the utility of monitoring is the trend
that monitoring was able to identify in the rate of spina bifida without anencephalus (Figure 1). From 1968 through 1972, the rate exceeded 10 per 10,000 live births. Subsequently, the rate declined to approximately 1 per 10,000 live births in 1995, a decline of roughly 90%. This means a decline from roughly 30 cases in 1968 to 12 cases in 1995 in the Atlanta metropolitan area despite the increased size of the population. An equally marked trend has been noted for anencephalus.
Figure 1. Prevalence at Birth of Spina Bifida without Anencephalus, MACDP, 1968-1995

The second source of cases is the records of the two pediatric hospitals that serve the catchment area. Abstracters at these hospitals review discharge summaries, disease indices, postmortem logs, laboratory logs, and surgery logs. Records are completed on all new cases detected by these means.
A third source of cases is information collected from cytogenetics laboratories. All records of infants with abnormal karyotypes are available from the laboratories for review. Every 6 months, a list of records identified through other sources that indicate pending cytogenetic studies is provided to the abstracter who visits the genetic laboratory for follow-up.
The fourth major source of MACDP cases is the vital records system, which records some birth defects cases that are not picked up through the other sources. Periodically we review Georgia Department of Human Resources live birth, spontaneous abortion, stillbirth, and infant death certificates that record the presence of a birth defect.
Uses of the data During its history, the MACDP database has helped to
evaluate in utero exposures to potential or suspected teratogenic factors such as Agent Orange, antiepileptic drugs, tranquilizers, cocaine, and chorionic villus sampling. In addition, CDC staff members routinely monitor for increases in the rates of specific defects as a sign of the introduction of a new teratogen. Twice a year the MACDP applies statistical tests to the accumulated data to see if there have been significant deviations from the baseline rates. Such deviations generate "flags." The deviations thus "flagged" are then subject to further discussion and analysis in an attempt to explain them. No new teratogens have been detected by this practice, but the trends, both upward and downward, do provide useful measures of the impact of various clinical and social changes.

Some decline was expected because of the increasing use of prenatal diagnosis and elective pregnancy termination beginning in the 1980s. A study done by Helen Roberts, MD, and colleagues at CDC attempted to measure what percentage of neural tube defect (NTD) cases were missed by MACDP surveillance during 1990 and 1991 because affected pregnancies were electively terminated before 20 weeks1. When the terminated cases were added in, Roberts et al were able to identify a total of 87 recognized, NTD-affected pregnancies during this time period: 37 anencephaly, 39 spina bifida, and 11 encephalocele. Twenty eight (32.2%) of these 87 pregnancies had been terminated. By type, the termination percentage was 48.6% for anencephaly, 23.1% for spina bifida, and 9.1% for encephalocele. The failure to record 32.2% of NTD cases because affected pregnancies were terminated before 20 weeks thus could have accounted entirely for the decline from roughly 6 NTD cases per 10,000 in 1980, just before the advent of widespread prenatal diagnosis, to roughly 4 per 10,000 in 1990-1991.
Terminations, however, cannot explain the decline before 1980, when the rate fell from 12 to 6 NTD cases per 10,000 live births. This suggests that some other factor or factors were involved, such as a possible improvement in folate intake. In this example, surveillance has not identified a new teratogen but it has produced useful information. It has also convinced CDC that, because of the difficulty in estimating the true incidence of NTDs when the picture is complicated by prenatal screening and elective pregnancy termination, some sort of ongoing prenatal surveillance is necessary. Such a system is being pilot tested now.

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Down Syndrome Increasing Another example of the utility of surveillance data is the
information derived from tracking the rates of Down syndrome in Atlanta (Figure 2). These rates have climbed from 9.5 per 10,000 live births in 1968-77, the first 10 years of the program, to 10.4 per 10,000 live births in 1986-95. One might have expected rates to decline because of the introduction and rapid adoption of prenatal diagnosis and elective pregnancy termination over this time period. In a study of the incidence of Down syndrome in Atlanta from 1970 through 1989, Krivchenia et al2 found the first records of aborted Down syndrome fetuses in the 1974-75 time period, when 2 (4.1%) of 49 affected pregnancies were terminated. The proportion of terminated pregnancies increased thereafter until, during 1988-89, 37 (32.4%) of 114 Down-syndrome-affected pregnancies were terminated.
Figure 2. Prevalence at Birth of Down's Syndrome, MACDP, 1968-1995
Krivchenia et al noted that the incidence of Down syndrome cases (live births plus terminations of affected pregnancies) increased between 1970 and 1989 and demonstrated that it was entirely explained by an increase in the average maternal age and the known strong association between this syndrome and advanced maternal age. For example, the proportion of children whose mothers were 30 years or older when they were born in Metropolitan Atlanta increased from 16% in 1968-73 to 29% in 1984-88. The percentage increased further to 38% in 1993. The proportion of terminated affected pregnancies during the 1990s is not known. However, if the proportion terminated did not increase above the 32% observed in 1988-89, then the further increase in the proportion of older mothers by 1993 could account for the increase in MACDP Down syndrome rates during the 1990s.
Baseline Rates of Defects Surveillance data can also be used to calculate baseline
rates of types of congenital anomalies. State and county health departments can use these figures to compare with local rates. They also can use them in planning for medical services for children with special health needs. Table 1 provides the rates of various selected categories of birth defects in Atlanta from 1991 through 1995.

More than 200 specific defect categories are monitored by the MACDP. Rates of other defects by year, gender, and race are available by calling Len Paulozzi, MD, MPH, at 770-4887172.

Table 1. Prevalence of Types of Defects at Birth in Metropolitan Atlanta, 1991-1995

Defect Type

Rate per 1,000 Live Births

Central nervous system

2.1

anencephaly

0.2

spina bifida

0.3

microcephalus

0.4

Eye

2.2

Ear

2.9

Cardiovascular

7.1

ASD

3.6

VSD

2.4

Respiratory

1.6

nose

1.0

Gastrointestinal

4.8

cleft lip

0.9

pyloric stenosis

1.1

Sex organ

5.2

hypospadias

2.6

Urinary tract

1.9

Musculoskeletal

8.3

club foot

1.3

Limb reductions

0.5

Skin

2.6

Endocrine

0.2

Autosomal chromosomal

1.7

Down syndrome

1.0

One or more defects

26.1*

* The sum of the rates for individual defect types exceeds 26.1 per 1,000 because some children have more than one defect.

References 1. Roberts HE, Moore CA, Cragan JD, Fernhoff PM, Khoury
MJ. "Impact of prenatal diagnosis on the birth prevalence of neural tube defects, Atlanta, 1990-1991". Pediatrics 1995; 96:880-883.
2. Krivchenia E, Huether CA, Edmonds LD, May DS, Guckenberger S. "Comparative epidemiology of Down syndrome in two United States populations, 1970-1989". Am J Epidemiol 1993; 137:815-828.

This report was contributed by Len Paulozzi, MD, MPH, Division of Birth Defects and Developmental Disabilities, National Center for Environmental Health, Centers for Disease Control and Prevention.

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The Georgia Epidemiology Report Epidemiology and Prevention Branch Two Peachtree St., NW Atlanta, GA 30303-3186

August 1997

Volume 13 Number 8

Reported Cases of Selected Notifiable Diseases in Georgia Profile* for May 1997

Selected Notifiable Diseases Campylobacteriosis

Total Reported for May 1997 19

Previous 3 Months Total

Ending in May

1995

1996

1997

247

184

78

Previous 12 Months Total

Ending in May

1995

1996

1997

888

950

672

Chlamydia genital infection Cryptosporidiosis

1797 0

2762 0

3063 13

4495 2

4368 0

12415 20

14853 81

E. coli O157:H7

5

1

7

10

4

36

53

Giardiasis Gonorrhea Haemophilis influenzae (invasive)

12 1792
2

120 4952
16

146 4524
16

111 4900
6

343 8547
32

623 21300
40

843 19354
43

Hepatitis A (acute)

33

34

103

117

63

165

463

Hepatitis B (acute)

7

Blood Lead Level > 10 g/dL (cap)

194

Blood Lead Level > 10 g/dL (ven)

93

Legionellosis

0

Lyme Disease

0

Meningococcal Disease (invasive)

7

45

3

37

708

711

612

140

124

242

6

3

0

9

1

0

24

50

36

97 1026
208 17 11 60

33 3011
623 8 6
142

110 2896
784 0 1
118

Mumps

0

2

1

3

4

9

12

Pertussis Rubella

0

4

11

3

16

37

29

0

0

0

0

0

0

0

Salmonellosis

71

245

220

220

1159

1685

1436

Shigellosis Syphilis - Primary Syphilis - Secondary

30

407

142

159

1676

931

1220

12

60

43

38

199

273

182

34

153

116

98

509

620

450

Syphilis - Early Latent

104

459

336

343

1609

1521

1276

Syphilis - Other** Syphilis - Congenital

113

269

247

356

811

1137

1140

3

12

11

7

35

66

24

Tuberculosis

46

183

222

188

634

808

737

* The cumulative numbers in the above table reflect the date the disease was first diagnosed rather than the date the report was received at the state office; and therefore are subject to change over time due to late reporting. The 3 month delay in the disease profile for a given month is designed to minimize any changes that may occur. This method of summarizing data is expected to provide a better overall measure of disease trends and patterns in Georgia.

** Other syphilis includes latent (unknown duration), late latent, late with symptomatic manifestations, and neurosyphilis.

Report Period

Total Cases Reported *

AIDS Profile Update

Percent

Risk Group Distribution (%)

Race Distribution (%)

Female

MSM IDU MSM&IDU HS Blood Unknown White Black Other

Last 12 Mos 08/96 to 07/97 5 Yrs Ago 08/91 to 07/92 Cumulative 01/80 to 07/97

2078 1991 18066

21.8

37.8 18.1

4.5

14.0

51.0 23.6

7.6

14.8

51.1 18.9

5.9

16.9 1.2

21.2

9.6 1.9

5.2

11.3 2.0

10.0

27.2 70.2 2.7 38.8 59.4 1.8 40.0 58.0 2.0

MSM - Men having sex with men IDU - Injection drug users HS - Heterosexual * Case totals are accumulated by date of report to the Epidemiology Section

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