GIS and Health Geography, Part II — Epidemiology, 2 March 2015
There are many applications for GIS within the field of health geography. Four of these include the study of spatial epidemiology, the study of environmental hazards, modeling health services, and identifying health inequalities.
Spatial epidemiology investigates the spatial patterns of disease and risk of disease. The scale of spatial epidemiology is at the individual and small area level, rather than the population level. Several issues that arise in this field of work are spatial misalignment due to minor difference that have large impacts at the small-area level and general uncertainty in the data, whether due to collection or the inherent nature of the information. Best practices have been defined to reduce these issues. The classic example of spatial epidemiology is Dr. John Snow’s map of cholera deaths in 1854.
Environmental hazards are addressed by the CDC in a stepwise fashion in an attempt to understand and prevent disease. Their process involves hazard surveillance, exposure surveillance, and outcome surveillance. GIS can be used to identify causes or mitigating factors.
GIS can also assist governments and other agencies with modeling the distribution and success of health services. One example of this use is Accessibility/Remoteness Index of Australia (ARIA). This is a “generic index of accessibility/remoteness for all populated places that are non-metropolitan.” It is useful for comparing results across different studies and identifying relationships across Australia.
GIS can be used to identify health inequalities based on previously known relationships. For example, the relationship between socioeconomic status and heart disease can be mapped to help identify what part location plays in the relationship.
In general, epidemiology is “the study of the distribution and determinants of health and disease-related states in populations, and the application of this study to control health problems.” There are many different approaches to this field of study, including descriptive and analytic approaches. Again, the question of health as differentiated from disease arises, and the understanding of these two concepts dictates the decisions people make.