Are health inequalities increasing in Japan? The trends of 1955 to 2000.

This study aimed to elucidate trends in socioeconomic inequalities in health during the past half century in Japan. Association of life expectancy and age-adjusted mortality with per capita income was examined using data on prefectures and municipalities in Japan of 1955 to 2000 via the slope index of inequality (SII) and Poisson regression. Although there were a few differences among health indicators and sex, health inequalities by prefecture, measured by the SII, decreased from 1955 to 1995. However, health inequalities increased from 1995 to 2000 both for life expectancy and mortality. Similar trends were found in municipal analyses: the association between income and mortality, measured by the rate ratio from Poisson regression, decreased until 1995 but increased from 1995 to 2000. In the past half century, and especially until 1995, geographical health inequalities decreased in Japan, while from 1995 to 2000 health inequalities appeared to increase. Recent social conditions including the possible increase in social inequalities may have contributed to this increase. Careful monitoring and elimination of social and health inequalities should be encouraged.