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CASE-CONTROL STUDY OF AIR QUALITY AND BIRTH DEFECTS: COMPARISON OF GEOCODED AND NON-GEOCODED POPULATIONS
Citation:
Mendola, P, S. Gilboa, Olshan. AF, A. H. Herring, P. Langlois, AND C. Harness. CASE-CONTROL STUDY OF AIR QUALITY AND BIRTH DEFECTS: COMPARISON OF GEOCODED AND NON-GEOCODED POPULATIONS. Presented at Society for Epidemiologic Research, Salt Lake City, Utah, June 15-18, 2004.
Description:
Unbiased geocoding of maternal residence is critical to the success of an ongoing 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. Geocoding was performed in ArcGIS 8.3 using ESRI ? StreetMap as the geocoding service for 5,338 cases and 4,574 controls. 4582 (85.8%) cases and 3669 (80.2%) controls were successfully geocoded. In both the geocoded and non-geocoded groups, case mothers were more likely than control mothers to be over age 35 (Odds Ratiogeocoded = 1.57; 95% Confidence Interval = 1.38-1.79 and ORnon-geocoded = 1.50; 1.10-2.04), and delivered preterm (ORgeocoded = 2.88; 2.56-3.24 and ORnon-geocoded = 3.08; 2.39-3.98). The racial distribution was significantly different between the geocoded and non-geocoded for both cases and controls. In the non-geocoded population, cases were significantly more likely than controls to be white than in the geocoded population (ORgeocoded = 1.06; 0.94-1.19 and ORnon-geocoded = 1.72; 1.27-2.34). Overall the geocoded sample appears comparable to the non-geocoded sample, although the potential for selection bias remains 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