| Comparison of Different Methods for Spatial Analysis of Cancer Data in Utah Wayne Ball,1 Sam LeFevre,1 Lars Jarup,2 and Linda Beale2 1Environmental Epidemiology Program, Utah Department of Health, Salt Lake City, Utah, USA; 2Small Area Health Statistics Unit, Imperial College London, London, UK Abstract
Background: The standardized incidence ratio (SIR) and SaTScan software are used by the Environmental Epidemiology Program (EEP) , Utah Department of Health, to investigate health concerns and exposures in Utah (USA) . Recently, the EEP acquired the Rapid Inquiry Facility (RIF) . The RIF enables access of additional dimensions of data, identifies potentially exposed populations, and computes disease rates and relative risk statistics for that potentially exposed population. Objective: In this article we present a comparison of the SIR, SaTScan, and RIF methodologies in an investigation of cancer rates in residents living over contaminated groundwater plumes near Hill Air Force Base (HAFB) in Utah. Methods: For this study, we used cancer data from the Utah Cancer Registry for cancers of the lung, kidney, and non-Hodgkin lymphoma. We used SIR and the RIF to investigate the cancer rate in a defined population within the study area during six consecutive 5-year time intervals (1975–2004) . We used SaTScan and the RIF to explore the study area for clusters. Results: The RIF risk analysis and SIR are mathematically identical. SIR is set up and computed by programming SAS ; the RIF risk analysis, on the other hand, is set up through four menu-driven steps. The RIF disease-mapping feature enhanced the interpretation of SaTScan results. We found kidney and lung cancer to be statistically elevated for the potentially exposed population for one and two periods, respectively. SaTScan found two clusters, one outside the potentially exposed population and one that included a portion of that population. Conclusion: The RIF is an easy-to-use and useful tool that extends the ability of the investigator to conduct analysis of disease rates and interpret the findings. Key words: cancer, exposure assessment, risk assessment, statistics. Environ Health Perspect 116:1120–1124 (2008) . doi:10.1289/ehp.10815 available via http://dx.doi.org/ [Online 25 April 2008]
This article is part of the mini-monograph on spatial epidemiology. Address correspondence to S. LeFevre, Utah Department of Health, Environmental Epidemiology Program, P.O. Box 142104, Salt Lake City, Utah 84114-2104 USA. Telephone: (801) 538-6191. Fax: (801) 538-6564. E-mail: slefevre@utah.gov This work was supported, in part, by grants U50/CCU822437 and 1-U38-EH000182 from the U.S. Centers of Disease Control and Prevention (CDC) . Data for this work were provided by the Utah Cancer Registry (UCR) , which is funded by contract N01-PC-35141 from the National Cancer Institute, with additional support from the Utah Department of Health (UDOH) and the University of Utah (UU) . The contents of this work are solely the responsibilities of the authors and do not necessarily represent the official views of the CDC, UCR, UDOH, or UU. The authors declare they have no competing financial interests. Received 28 August 2007 ; accepted 25 April 2008.
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