Association Between Ambulance Distance to Hospitals and Mortality from Acute Diseases in Japan: National Database Analysis

Objective: The aim of this study was to evaluate the relationship between ambulance distance to hospitals and mortality from acute diseases using the national database in Japan. Design: Geospatial ecological study. Setting: We collected the data of transport distance to hospitals from the Diagnosis Procedure Combination database and that of mortality per 100 000 from some acute diseases from the database of life tables by the Ministry of Health, Labour and Welfare in Japan. Participants: A total of 108 314 patients (40 882 patients with acute myocardial infarction, 31 632 patients with brain infarction, 4992 patients with subarachnoid hemorrhage, and 30 808 patients with pneumonia) were referred in Japan in 2008. Main Outcome Measures: We evaluated the association between the mean transport distance to hospitals and the mortality from acute diseases using simple linear regression analysis. This correlation was evaluated separately for each acute disease. Results: The mean transport distances to hospitals were 8.1 km for acute myocardial infarction, 8.3 km for brain infarction, 9.5 km for subarachnoid hemorrhage, and 7.6 km for pneumonia, whereas the mortalities per 100 000 were 34.6 for acute myocardial infarction, 60.4 for brain infarction, 11.2 for subarachnoid hemorrhage, and 91.6 for pneumonia. Simple linear regression analysis revealed significant positive correlations between transport distance and mortality per 100 000 for acute myocardial infarction and brain infarction (R-2 = 0.315 and 0.398, P < .001, respectively). Otherwise, moderate positive correlations between transport distance and mortality per 100 000 were shown for subarachnoid hemorrhage and pneumonia (R-2 = 0.112, P < .012 and .233, P < .001, respectively). Conclusions: This study suggests that the ambulance distance to hospitals significantly influences the risk of mortality for some acute diseases in Japan. Further studies are needed to confirm this association.