Geographical Differences and Their Associated Factors in Chronic Obstructive Pulmonary Disease Mortality in Japan: An Ecological Study Using Nationwide Data

Geographical differences in chronic obstructive pulmonary disease (COPD) mortality have not been determined using municipal-specific data in Japan. This study determined the geographical differences in COPD mortality in Japan using municipal-specific data and identified associated factors. Data on COPD mortality from 2013 to 2017 for each municipality were obtained from the Vital Statistics of Japan. We calculated the standardized mortality ratio (SMR) of COPD by an empirical Bayes method for each municipality and located the SMRs on a map of Japan. In addition, an ecological study was conducted to identify factors associated with the SMR using demographic, socioeconomic, and medical characteristics of municipalities by a spatial statistics model. Geographical differences in the SMR were different in men and women, and municipalities with a low SMR tended to be more frequent in women. Spatial regression analysis identified that the total population and taxable income per capita were negatively associated with the SMR in men. In women, population density, the proportion of fatherless households, and the number of clinics per capita were positively associated with the SMR, whereas taxable income per capita was negatively associated with the SMR. There were some differences in regional characteristics associated with COPD mortality by sex.