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RELIANCE ON GEOCODED MATERNAL RESIDENCE: IMPACT ON A POPULATION-BASED CASE-CONTROL STUDY OF AIR QUALITY AND BIRTH DEFECTS
Citation:
Gilboa, S., P Mendola, A. F. Olshan, C. Harness, A. H. Herring, AND P. Langlois. RELIANCE ON GEOCODED MATERNAL RESIDENCE: IMPACT ON A POPULATION-BASED CASE-CONTROL STUDY OF AIR QUALITY AND BIRTH DEFECTS. Presented at Teratology meeting, Vancouver, BC, Canada, June 26-July 1, 2004.
Description:
Introduction: Unbiased geocoding of maternal residence is critical to the success of an ongoing population-based case-control study of exposure to five criteria air pollutants and the risk of selected birth defects in seven Texas counties between 1997 and 2000. The geocoded residence at delivery will be used to assign exposure during the critical window of gestational weeks three through eight using ambient pollution concentrations measured at the monitor closest to the home. Methods: Geocoding was performed in ArcGIS 8.3 using ESRI ? StreetMap as the geocoding service for 5,338 cases and 4,574 controls. We compared vital record data for geocoded and non-geocoded cases and controls. Results: 4582 (85.8%) cases and 3669 (80.2%) controls were successfully geocoded. There were differences between the geocoded and non-geocoded populations by race (83% white vs. 87% white) and ethnicity (52% Hispanic vs. 60% Hispanic). In the non-geocoded population, cases were significantly more likely than controls to be white than in the geocoded population (OR geocoded = 1.06; 95% CI = 0.94-1.19 and OR non-geocoded = 1.72; 95% CI = 1.27-2.34). In both the geocoded and non-gecoded groups, case mothers were more likely than control mothers to be over age 35 (Odds Ratio geocoded = 1.57; 95% Confidence Interval = 1.38-1.79 and OR non-geocoded = 1.50; 95% CI = 1.10-2.04) and delivered preterm (OR geocoded = 2.88; 95% CI = 2.56-3.24 and OR non-geocoded = 3.08; 95% CI = 2.39-3.98) and low birth weight (OR geocoded = 5.54; 95% CI = 4.78-6.42 and OR non-geocoded = 5.42; 95% CI = 5.39-7.47) infants. The association between absence of prenatal care and case status was slightly more pronounced in the non-geocoded population (OR geocoded = 1.32; 95% CI = 0.98, 1.76 and OR non-geocoded = 2.03, 95% CI = 1.20, 3.44). Discussion: Overall, the geocoded sample appears comparable to the non-geocoded sample, although the potential for selection bias exists if factors on which they differ are associated with air pollution exposure. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy