Development of methodology for identifying spatial links between environmental exposure and disease prevalence

Read, Jessica Sian 2007. Development of methodology for identifying spatial links between environmental exposure and disease prevalence. PhD Thesis, Cardiff University.

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Abstract

The recent increased availability of geographically linked individual level health outcome data and improvements in exposure mapping techniques, which furnish point exposure estimates, motivate the development of spatial statistical methodology that takes full advantage of individual level data. Kernel density estimation is a powerful tool for mapping the risk of a health outcome that uses individual level data. Development of kernel density methodology has provided a global significance test for regions of elevated relative risk and a test for the spatial association between a health outcome and environmental exposure. Comparisons with some existing spatial statistical techniques highlight the strengths of the kernel density based methods. Moreover, simulation exercises indicate that the kernel density test for spatial association is a more powerful testing procedure than the most popular standard test proposed by Stone. Kernel density estimation and the global significance test for regions of elevated relative risk are illustrated for congenital malformations around a landfill site and sex ratios in Cardiff and the Vale of Glamorgan. The application of these methodologies revealed that both birth outcomes had a statistically significant heterogeneous spatial pattern over the relevant study regions even after adjustment for known confounders. Good quality, high resolution environmental exposure data was unavailable and prevented a direct application of the kernel density test for spatial association with a health outcome. However, the test can be applied to any two relative risk/density surfaces and was used to compare the spatial patterns of chromosomal and non-chromosomal anomalies in the region of the Nant y Gwyddon landfill site. It was concluded that the spatial patterns for the two sets of anomalies were different. The test was also used to assess the quality of the adjustment for confounders when producing expected risk surfaces and the adjustment was found to be adequate.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Medicine
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences R Medicine > RA Public aspects of medicine R Medicine > RB Pathology
ISBN:	9781303209437
Funders:	MRC
Date of First Compliant Deposit:	30 March 2016
Last Modified:	12 Feb 2016 23:12
URI:	https://orca.cardiff.ac.uk/id/eprint/54602

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