都道府県別に見た世帯所得の分布と平均寿命の変化 : 地域の所得格差は健康を損なうか

There is concern being voiced in Japan about the growing inequality of income distribution in the
past two decades. This study aimed to elucidate trends in socioeconomic and health inequalities.
Some of large variations in income distribution can be explained by changes in the economy and the
demography: the deepening of the recent recession, the rapidly aging population and the decline of
average family size. From the view point of regional sciences as geography, it is important to
distinguish the inter-regional inequality and the intra-regional inequality. On the other hand in
social epidemiology, a large number of studies have demonstrated health inequalities attributable to
socioeconomic conditions including income. Is the degree of income inequalities in society closely
linked to the health of the population? Association of life expectancy at birth (LEB) with adjusting
household incomes by equivalence scales was examined using data on prefectures in Japan of 1995
to 2005 via Pearson's correlation and OLS regression. Although inter-regional inequality of median
income level decreased, intra-regional inequality measured by inter-quartile range increased from
1993 to 2003. There is a gender difference in correlation coefficient between health indicators and
income inequalities. In case of male positive correlations were found between LEB and
inter-regional inequality (absolute income hypothesis), and negative correlation between LEB and
intra-regional inequality (relative income hypothesis). The both association increased from 1995 to
2005. Careful monitoring of socioeconomic and health inequalities should be encouraged.