Spatial analysis for epidemiology and health geography

This article is an introduction to spatial analysis for epidemiology and health geography. It aims to describe the objectives, concepts, methods and techniques available in this field. It is aimed at students and professionals in public health, epidemiologists, public health inspectors, health geographers and specialists in health-environment relations, whether in human or animal health. It is also intended for anyone seeking an introduction to the general methods of spatial analysis.

Spatial analysis includes any technique that studies objects and their relationships using their topological or geometric properties. This definition is very general and applies to many fields: spatial analysis has been used for many years in geography and epidemiology, but also in biology, botany, image processing, network analysis, electronics, chemistry, climatology, hydrology and economics...

In epidemiology (the study of factors influencing health and disease in a population) and health geography (geographical analysis of the healthcare system and the spatial distribution of disease), the term spatial analysis is used to describe analysis techniques applied to the "objects" described by epidemiology or geography, as long as they are located in space (individuals, vectors, reservoirs, populations, territories, the natural environment, the urban environment, etc.). What is excluded is what happens "inside" the patient (in the organ, in the cell, or at the level of the pathogen's biology). For example, this article does not deal with medical imaging and associated image processing techniques, even though some of these techniques are sometimes very similar to those we will be describing.

Health phenomena are rarely randomly distributed in space. Indeed, health phenomena often involve risk factors linked to geographical factors, environmental factors and spatial relationships between individuals. The use of location is therefore fundamental to the analysis and understanding of health phenomena and their mechanisms: by taking into account the spatial relationships and interactions between the actors involved in a disease – seen as a complex system – spatial analysis enables us to better identify and understand the mechanisms and processes underlying these phenomena. Spatial analysis in epidemiology thus offers elements that consolidate "classical" epidemiology and enrich the approach of other disciplines, particularly health geography. It includes cartographic analysis, the search for geometric and spatio-temporal characteristics, the analysis of the spatial continuity of a value, the search for aggregates, and so on.

In the healthcare sector, spatial analysis is not only used for epidemiological and geographical studies. It is also...