Proximity of residence to trichloroethylene-emitting sites and increased risk of offspring congenital heart defects among older women.

BACKGROUND: Previous studies suggest that trichloroethylene (TCE) is a selective cardiac teratogen. We tested the hypothesis that the odds of maternal residence close to TCE-emitting sites would be greater among infants with congenital heart defects (CHDs) than among infants without CHDs. METHODS: We conducted a case-control study of 4025 infants, identified from hospital and birth records, born from 1997 to 1999 to Milwaukee, Wisconsin mothers. A geographic information system was used to calculate distances between maternal residences and TCE sites. We used classification tree analysis to determine appropriate values by which to dichotomously categorize mothers by TCE exposure (exposed: residence within 1.32 miles of at least one TCE site) and age (older: >/=38 years), and logistic regression to test for CHD risk factors. RESULTS: The proportion of mothers who were both older and had presumed TCE exposure was more than six-fold greater among case infants than among control infants (3.3% [8/245] versus 0.5% [19/3780]). When adjusted for other variables, CHD risk was over three-fold greater among infants of older, exposed mothers compared to infants of older, nonexposed mothers (adjusted OR, 3.2; 95% CI, 1.2-8.7). Older maternal age, alcohol use, chronic hypertension, and preexisting diabetes were each associated with CHDs (adjusted ORs, 1.9, 2.1, 2.8, 4.1; 95% CIs, 1.1-3.5, 1.1-4.2, 1.2-6.7, 1.5-11.2, respectively), but residence close to TCE sites alone was not. CONCLUSIONS: Our findings suggest that maternal age and TCE exposure interact to increase CHD risk, although the mechanism by which this occurs is unknown. A prospective study is underway to confirm this finding.

Excess birth prevalence of Hypoplastic Left Heart syndrome in eastern Wisconsin for birth cohorts 1997-1999.

BACKGROUND: Hypoplastic Left Heart syndrome (HLHS) is a group of cardiac malformations involving underdevelopment of the left heart with an inability to maintain systemic circulation. Because of a clinical impression of excess HLHS prevalence, we completed a medical record review of cases born from 1997 through 1999 who were Wisconsin residents and seen at the Children's Hospital of Wisconsin (CHW). METHODS: Cases were identified either in the CHW medical records database or the Division of Pediatric Cardiology database and confirmed by echocardiogram, catheterization, surgery, or autopsy. U.S. and international surveillance systems were used to estimate population risk. Rates per 10,000 births were computed for eastern Wisconsin and four regions within this portion of the state, and compared to the estimated population risk. The same methods were used to evaluate whether rates for tetralogy of Fallot and transposition of the great arteries were elevated. RESULTS: A total of 61 cases were ascertained yielding a birth prevalence of 3.7 per 10,000 births, which was greater than the estimated population risk of 2.79. The rate for the southeast region also exceeded the expected rate. The most urban and industrialized areas had the highest rates. Rates for the other two diagnoses evaluated were not different from estimated population risks. CONCLUSIONS: Eastern Wisconsin, particularly the urban southeast region, had elevated rates of HLHS. Because of the geographic clustering of high rates, environmental factors may be associated with this finding.

Completeness of state administrative databases for surveillance of congenital heart disease.

BACKGROUND: Tracking birth prevalence of cardiac defects is essential to determining time and space clusters, and identifying potential associated factors. Resource limitations on state birth defects surveillance programs sometimes require that databases already available be used for ascertaining such defects. This study evaluated the data quality of state administrative databases for ascertaining congenital heart defects (CHD) and specific diagnoses of CHD. METHODS: Children's Hospital of Wisconsin (CHW) medical records for infants born 1997-1999 and treated for CHD (n = 373) were abstracted and each case assigned CHD diagnoses based on definitive diagnostic reports (echocardiograms, catheterizations, surgical or autopsy reports). These data were linked to state birth and death records, and birth and postnatal (< 1 year of age) hospital discharge summaries at the Wisconsin Bureau of Health Information (WBHI). Presence of any code/checkbox indicating CHD (generic CHD) and exact matches to abstracted diagnoses were evaluated. RESULTS: Fifty-eight percent of cases with generic CHD were identified by state databases. Postnatal hospital discharge summaries identified 48%, birth hospital discharge summaries 27%, birth certificates 9% and death records 4% of these cases. Exact matches were found for 52% of 633 specific diagnoses. Postnatal hospital discharge summaries provided most matches. CONCLUSION: State databases identified 60% of generic CHD and exactly matched about half of specific CHD diagnoses. The postnatal hospital discharge summaries performed best in both in identifying generic CHD and matching specific CHD diagnoses. Vital records had limited value in ascertaining CHD.