Page 1 of 3 Next  Steeve Ebener Project Manager, STK, e-Health World Health Organization Geneva, Switzerland ebeners@who.int Zine El Morjani World Health Organization, Switzerland elmorjaniz@who.int Nicolas Ray University of Bern, Switzerland nicolas.ray@zoo.unibe.ch Michael Black RMIT University, Melbourne, Australia michael.black@rmit.edu.au Public health and health care are important concerns for developing countries and access to health care is a significant factor that contributes to a healthy population. In response to these issues, the World Health Organization (WHO) has been working in collaboration with a number of academic institutions in Australia, Switzerland and Canada on the development of methods and models for measuring physical accessibility to health care using several layers of information integrated in a Geographic Information System (GIS). Two products have resulted from this work: AccessMod© and MAPA. An outline of these two products is presented here, specifically emphasising the transition from modelling the geographic extent of catchment areas using an isotropic function to the use of an anisotropic approach. Background Access to health care is an important component of an overall health system which has a direct impact on the burden of disease that affects many countries in the developing world. Measuring accessibility to health care therefore contributes to a wider understanding of the performance of health systems within and between countries which facilitates the development of evidence based health policies. Accessibility to health care is concerned with the ability of a population to obtain a specified set of health care services. In this context, geographic accessibility, often referred to as spatial or physical accessibility is concerned with the complex relationship which exists between the spatial separation of the population and the supply of health care facilities. The use of Geographic Information Systems (GIS) for the measurement of physical accessibility is well established and has been applied in many areas including retail site analysis, transport, emergency service and health care planning (e.g. Wilkinson et al 1998, Albert et al 2000 and Cromley & McLafferty 2002). In the context of health care planning, the ability of GIS to identify the geographic extent of a health facility catchment area, which corresponds to the area which contains the population utilising this facility, is a particularly important analytical capability. A number of techniques have been used within GIS to analyse physical accessibility to health care. Within urban areas, the most common techniques involve a vector approach which relies on high quality road network information, shortest path and route optimisation algorithms and incorporates the concept of 'competition' between the many potential health care providers. Over larger areas however, and in particular rural areas, raster GIS techniques are more commonly used as these approaches do not restrict 'movement' to just the physical road network and incorporate travel across the 'terrain'. The most common raster technique for analysing movements across a continuous surface is the cost-distance approach (Longley et al 2005) which calculate the 'cost of movement' between two points adding the cost contain in each cell on the way. Such techniques are commonly found in commercial GIS products such as in the ESRI Spatial Analyst extension. Depending on the mode of transportation that is considered, the travelling speed to the 'nearest' health facility may be significantly influenced by environmental factors such as slope and land cover. Measuring physical accessibility to health care using GIS therefore requires that the heterogeneity of the environment be taken into consideration in order to obtain results that are as close as possible to reality.
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