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July - September 2002
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Health Geography

GIS provides a holistic approach to public health that promotes the well being of human populations through organizing data about who we are, where we live, and how we live within a geographic framework.

The health of human populations reflects the complex interplay between population characteristics and the environment. Genetic makeup can predispose certain populations to chronic or acute conditions. Cultural factors, such as stress, economic status, and access to health care, can play a significant part in disease onset. For example, heart disease, cancer, and alcoholism--leading causes of death in the United States--are produced by multiple, interrelated factors rather than a single infectious agent.

GIS incorporates data that describes population characteristics, socioeconomic conditions, and the landscape, and analyzes the spatial relationship of these factors. In addition to integrating and analyzing health related data, this technology promotes data sharing through the use of standard formats and a highly efficient communication tool--the map.

Improving Research

Although GIS applications for market research, site location, and facilities management are used in the health industry, the classic use of GIS in the health arena has been public health. The Centers for Disease Control (CDC) and Prevention makes extensive use of GIS for investigating the cause and spread of deadly diseases such as polio, malaria, Guinea worm, and Lyme disease. As part of these efforts, CDC distributes Epi Map 2000 to public health practitioners and researchers around the world. Epi Map 2000 is a public domain GIS application developed by the CDC using Microsoft Visual Basic 6.0 and Esri MapObjects 2.0a. It comes with boundary data in shapefile format and is available at no cost.

The National Center for Health Statistics, the principal vital and health statistics agency for the United States and part of the CDC, showcases its use of GIS on its GIS and Public Health Web site. It provides information on GIS use by the public health community via its newsletter, features maps from the Atlas of United States Mortality, and has links to GIS-related sites.

In the 1970s, the National Cancer Institute (NCI) mapped cancer data that had been available in tabular form for years and immediately geographic patterns in the data emerged. The NCI's innovative work contributed significantly to understanding regional differences in rates of lung and oral cancers. Subsequently, NCI has made extensive use of GIS for spatial analysis and visualization of data as well as database development. The Long Island Breast Cancer Study Project exemplifies the NCI's use of GIS for cancer research.

Although rates for many types of cancer have declined, breast cancer remains the most common form of cancer in women, accounting for one in every three cancer diagnoses. In 1993, Congress mandated a study of the possible environmental causes of breast cancer on Long Island, New York. This mandate included the creation of a prototype GIS called GIS-H. AverStar, Inc., of Vienna, Virginia, developed GIS-H for NCI. GIS-H helps researchers study the relationship between environmental exposures and occurrences of breast cancer.

At the NCI Web site, visitors can use the Metadata Browser to navigate through the geographic, demographic, and health source datasets used by GIS-H, view Federal Geographic Data Committee (FGDC) metadata reports for geographic data, and review pertinent information about GIS-H Data Warehouse contents. Various levels of access have been built in to safeguard the confidentiality of data. GIS-H is designed primarily for researchers but a portion of the NCI Web site will feature mapping capability that will let the public view and use some of the content and features of GIS-H.

Targeting Resources

In some cases, while the cause of a health threat may be well understood, identifying at-risk individuals proves challenging. Despite federal regulations that removed lead from paint, gasoline, food cans, and other products, lead poisoning remains a leading health hazard for children in the United States between the ages of one and five. Elevated levels of lead can damage the brain and nervous system, and at very high levels, can cause death. Children in low-income housing areas are the most vulnerable to lead poisoning caused by ingesting chips or breathing dust from lead-based paint found in deteriorating pre-1950s houses.

Screening all young children for lead poisoning, as mandated by the federal government, has proved an expensive and formidable task that has not been especially effective in locating children suffering from lead poisoning. Although Medicaid pays for the cost of the test and treatment, the significant costs of screening are borne by each state's public health department.

The Indiana State Department of Health used GIS to target screening efforts in areas with housing inventory types, socioeconomic makeup, and other characteristics associated with lead poisoning. State health records were geocoded and an application, developed by a team at Ball State University in Muncie, provides regression analysis and predictive modeling that locates high incidence areas. By concentrating screening efforts, the State saved $2 million and identified many more children suffering from lead poisoning.

Improving Community Programs

The availability of powerful desktop GIS and spatially-enabled data has expanded the use of GIS beyond research institutes and state agencies to hospitals and medical centers. In addition to using GIS for organizing, linking, and presenting datasets, modeling local data can provide insights that lead to the development of programs that better serve the community.

Public health practitioners can use GIS marketing methodology to locate the most likely "customers" for prevention campaigns such as anti-smoking programs or cancer screening. The Late-Stage Breast Cancer Program sponsored by Baystate Medical Center in Springfield, Massachusetts, is an example of this type of GIS application. The program looks at women diagnosed with late-stage breast cancer during a 10-year period and evaluates factors such as community characteristics (e.g., educational attainment, socioeconomic status) and individual characteristics (e.g., age at diagnosis, distance to the nearest mammography center) that contribute to delayed diagnoses.

In addition to its increased use for public safety, GIS is also being incorporated into programs that safeguard public health against terrorist threats such as bioweapons. Although these threats may originate outside the country, initial response is always local. Monitoring disease levels in populations, maintaining current inventories of medicines and other supplies, and tracking the availability and location of trained personnel needed in emergencies are all activities enhanced by GIS.

Intelligent Use of GIS

Like all powerful technologies, GIS must be intelligently applied by practitioners versed in both public health methodologies and GIS. An understanding of epidemiological principles and methods is required to structure studies and interpret results. Mapping sophistication is necessary to generalize, symbolize, and classify data so that maps communicate effectively rather than distorting the data behind the map.

All consumers and custodians of medical data, not just GIS users, will be required by the Health Insurance Portability and Accountability Act (HIPAA) to maintain the confidentiality of medical records. The first of many regulations that protect patient privacy, HIPAA controls the dissemination of identifiable health data. Beginning in October 2002, HIPAA will require that organizations develop policies that prevent the identification of an individual's medical records. GIS is a helpful tool in formulating validation policies that prevent unintentional re-identification of individuals.

Expanding GIS Use for Health

Forces not specific to public health are also encouraging the spread of GIS. Data standardization and the development of the National Spatial Data Infrastructure support the use of GIS, not only for public health, but for all government and business applications. Geospatial boundary and demographic data is more readily available from government and commercial sources in a variety of vector and raster formats. An increasing percentage of vital statistics gathered by public health agencies are geocoded and public health practitioners are developing data partnerships.

The distribution of GIS software such as Epi Map 2000 and the development of Web-based GIS applications are putting GIS within the grasp of smaller organizations. Complementary technologies such as GPS and the development of ArcPad, a GIS for handheld devices, have made possible disease surveillance applications such as the one used by the State of Pennsylvania to monitor an outbreak of West Nile Virus.

Esri continues to support organizations that are pioneering GIS use for public health. Esri hosted the first International GIS Health Conference and has continued to aid the development of GIS tools for public health practitioners.

For more information, contact

Bill Davenhall
Esri Health and Human Services Solutions Manager
Tel.: 909-793-2853, ext. 1-1714

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