Wide range of socioeconomic factors associated with mortality among cities in Japan

The aim of this study was to identify socioeconomic factors associated with mortality among cities in Japan. Sex-specific and age-adjusted mortality rates for 1990 and 1995 were calculated by 779 local administrative units across the nation. One hundred indicators related to socioeconomic factors were compiled and divided into eight categories: economy, education, living conditions, vegetation and open space, transport, preventive activities, medical care and demography. Composite socioeconomic indices were formulated using factor analysis of the socioeconomic indicators by category, and the association between the indices and mortality rates was examined by correlation analysis and multiple regression analysis. Nineteen composite socioeconomic indices were obtained from factor analysis, and all indices except educational expenditure-related index were significantly correlated with mortality rates. Unemployment, old housing, primary health resources and density were independently positively associated, and higher education, public library activity, health check-up participation and population growth were independently negatively associated with both 1990 and 1995 male mortality rates. For female mortality, higher income, unemployment, spacious dwelling, old housing, less vegetation, road facility, numbers of cars per population, primary health resources and density were independently positively associated, and higher education, public library activity and health check-up participation were independently negatively associated. The relationship between mortality and socioeconomic conditions was stronger in males than in females, and higher income and less vegetation were associated with higher mortality only for females. The present study demonstrated a close link between mortality and a wide range of socioeconomic conditions by using a number of indicators compiled from various data sources. The results promote a deeper understanding of socioeconomic health determinants and development of multi-sectoral health policy to improve population health.