Linking GIS Technology
with Essential Public Health Services

WE PREDICT THAT, by the year 2010, GIS applications in public health practice will no longer consist of the ad hoc approaches we have seen in the 1990s. By the year 2010, we expect to see GIS technology customized for public health applications. This GIS health software will offer applications that "know" which data systems are needed and where they are located. After loading the appropriate data and performing relevant analyses, the system will offer alternative courses of action ranging from informing other people in the public health system to issuing health advisories.

In what follows, we give several examples of the way public health practitioners are likely to routinely use GIS technology in the year 2010, organized according to the 10 consensus "essential public health services" identified in 1994 by US Public Health Service agencies and major national public health organizations.( 29-31 ) CDC is currently pilot-testing performance standards for state and local public health systems based on this framework (for more details, see the National Public Health Performance Standards Program's website).

Monitor health status to identify community problems. As part of a community health report card, a local public health department -- serving a county with 300,000 population and 10 high schools -- wants to map adolescent pregnancy rates for each high school's attendance area. In a secure environment in which the confidentiality of individuals and individual households is protected, the department codes the street address of each pregnant adolescent and prepares a smoothed (spatially filtered) map of adolescent pregnancy rates using a set of overlapping circles of fixed size. Next, using GIS software, school attendance boundaries are superimposed over the smoothed map. In addition to maps displaying the entire jurisdiction, higher magnification views are developed for each school attendance area, accompanied by a chart with summary statistics on use of prenatal care services, by trimester of pregnancy. The map is used to engage parents, faculty, and students in dialogue about how to best develop and target specific interventions for each district.

Diagnose and investigate health problems and hazards in the community. An epidemiologist in a large urban public health department scans electronic inpatient and outpatient medical records for all hospitals and managed care plans in the community. She uses the data to map asthma cases and compares maps for the current week with those for prior time periods. Inspecting the maps for unusual case clusters or patterns, she finds a new pattern of increased asthma hospitalizations. She expediently "visits" the hospital with the highest rate and reviews the cases. Eight of 10 affected individuals work at the same factory. Subsequently, using GIS technology linked to a "worker right to know" database about workplace chemical exposures, the epidemiologist reviews the potential exposures at the factory and identifies the agents associated with asthma-related hospital admissions. The epidemiologist then requests that an industrial hygienist visit the plant the same day.

Inform, educate, and empower people about health issues. One of a community's identified priorities is to develop an anti-smoking campaign. An anti-smoking coalition uses GIS technology and commercial lifestyle segmentation profiles (or a public health analogue developed by CDC by 2010) to identify subgroups that are most likely to include active smokers, the Census blocks where active smokers are most likely to reside, and the most effective communication media and times of day to deliver anti-smoking messages to these subgroups.

Mobilize community partnerships and action to identify and solve health problems. A community identifies childhood immunization levels as a priority. The local public health department wants to engage the faith community as part of an initiative to increase immunization rates. The department maps the locations of churches in areas with the highest numbers of young children. The ministers of these churches are invited to a meeting, where they decide to join together as a work group to develop appropriate health promotion materials and intervention strategies. During a subsequent meeting, the work group uses GIS technology to develop maps of the locations of school clinics and childcare centers within an inner-city area. Additional maps are used to assign church volunteers to school clinics and childcare facilities so travel distance is minimized. Maps are also developed to evaluate geographic patterns of children with missed immunization appointments, to help target educational interventions.

Develop policies and plans that support individual and community health efforts. The local public health department prepares a map to show the location of each health clinic in the community (including those run by hospitals and managed care plans, as well as those run by public health agencies). Another map is prepared that shows the residences of Medicaid-eligible individuals who use each clinic location. Using GIS technology, community decision makers overlay these maps and use the resultant patterns to help develop plans for better utilization of existing health care resources.

Enforce laws and regulations that protect health and ensure safety. To better provide neighborhood-level services, a local public health agency organizes its services by geographic areas, with a different subdivision of the agency responsible for each service area. Under this new system, environmental complaints need to be assigned to the correct service area. In some cases, an address on one side of the street belongs to one service area while an address on the other side of the street belongs to a different area. Using a Web-enabled public access GIS database, the agency GIS manager extracts geographic boundary files for street addresses and for the boundaries of the service areas. Using a GIS program, the manager creates a geographic polygon for each area and uses "point-in-polygon" assignment procedures to allocate street addresses to the correct service areas. When the agency receives an environmental complaint, the street address is initially processed through a computer program that standardizes the address in conformance with US Postal Service standards (correcting spelling errors, verifying the existence of the address on the computerized system, and so on). The complaint is then automatically assigned to the appropriate service area based on the standardized street address.

Link people to needed personal health services and assure the provision of health care when otherwise unavailable. A non-English-speaking, foreign-born person entering the United States is identified as having tuberculosis (TB). This individual also has a severe heart problem that requires medication. A TB outreach worker uses a GIS health care access map to identify the nearest cardiologist who speaks the same language as the patient. Again using GIS technology, the TB outreach worker also produces a public transportation map printed both in English and in the patient's language that shows the patient how to travel to the physician's office.

Assure a competent public health and personnel health care workforce. CDC is planning a distance-based training program (via satellite) on TB prevention in foreign-born people who have recently entered the United States. CDC uses a GIS map to identify public health departments in areas with large numbers of such individuals; these departments are invited to participate. During the teleconference, the geographic origins of phone calls are automatically displayed on a GIS map to help identify callers and to monitor the number and locations of the callers on "hold."

Evaluate effectiveness, accessibility, and quality of personal and population-based health services. A local public health department prepares GIS maps showing its service delivery points as well as other community health resources. These maps include details about: units of service provided at each location; expenditures; and demographic information such as poverty level for each program participant. By linking clinical data with these maps, the department is able to evaluate whether resources are being deployed optimally to address priority health needs and to evaluate the effect of services on selected preventable health outcomes.

Research for new insights and innovative solutions to health problems. A graduate student in geography conducts an urban morphology study, mapping the history of population growth and forecasting the evolving shape of the city and public transportation needs. Several high-resolution digital earth images, taken over a period of one year, are available for an area under development. The student electronically imports these images and uses automated change detection to determine the changes over a one-year period, for example, the addition of housing developments, roads, landfills, and other features. This information is included in a community health report card and used to help establish community priorities and plans.

Public Health Reports 1999;114:366-367
This article reproduced with the permission of Oxford University Press.