Introduction: For an equitable distribution of health resources, resource-allocation policies focus on rural and also remote areas, assuming that these areas are underserved. However, definitions of 'rural' and 'remote' vary, and are not necessarily synonymous with 'underserved'. This Japanese study evaluated the association between the rurality/remoteness of the community in which a patient lives and his/her geographic accessibility to dialysis facilities.
Methods: Based on 1867 communities (census blocks) in Hiroshima Prefecture, Japan, predictive powers of five community-level rural/remote parameters (population size, population density, elderly rate, agriculture rate, and distance to the nearest city) were evaluated to identify communities where dialysis patients had a longer commute time to dialysis facilities. The proportion of low-access communities was examined when those communities were merged to form larger geographic units (four-level stepwise merger). One-way driving times of dialysis patients were used as the access parameter of a community and were calculated using geographic information systems based on the addresses of all the 7374 patients certified by municipalities as having renal disability, and on the addresses and capacities of all 98 dialysis facilities in Hiroshima.
Results: The average driving time was negatively correlated with population and population density, and positively correlated with elderly rate, agriculture rate, and distance to nearest city. When low-access was defined as >20, >30 & >40 min driving time, all rural/remote parameters showed better sensitivities (range 63.5-94.9%) than specificities (55.2-77.9%) to identify low-access communities, and positive predictive values were less than 50% for most parameters. When low-access was defined as >30 min driving time, the proportion of low-access communities substantially decreased when the geographic unit was expanded. In the administrative 'rural' area, the largest geographic unit, the percentage of low-access communities was 30%.
Conclusions: In any definition of 'rural/remote', and in any definition of 'low-access', the rural/remote areas contain a substantial proportion of high-access communities. In addition, a substantial proportion of low-access communities was excluded from rural/remote areas. The accuracy of the term 'low-access' deteriorated when the geographic unit of analysis was expanded. In order to identify underserved areas precisely, it is necessary to set the geographic unit of analysis as small as possible and measure the geographic accessibility itself, rather than designate some areas as 'rural' or 'remote', based on conventional geographic/demographic/distance parameters.