[Geographication of centenarians and its related factors in Japan]

This study explores the factors associated with longevity in Japan by considering the geographic distribution of centenarians based on the 1990 population census. The proportion of centenarians was calculated based on the population of those aged 65 years or older. The findings were 11.0 males and 28.2 females per 100,000 people aged 65 years or older. In this analysis, the rate ratio, RR, was used as an index for fluctuation of centenarians by prefecture. RR is also the proportion of centenarians in a prefecture to that in the nation. When the RR of both sexes is over 100, the region is defined as high proportion and less than this as low proportion. The high proportion regions were located in the western part of Japan i.e. from the Chugoku to the Kyusyu district, the low proportion regions were located in the eastern part of Japan i.e. from the Tohoku to the Kanto district both sexes. The relationship between the geographical distribution of centenarians and environmental factors was analyzed. The correlation coefficient of the proportion of centenarians and the temperature as index of a regional difference was the highest among the factors investigated. After adjusting for mean temperature, the mean value of factors associated with a high quality of welfare work and of medical service, and that of having leisure time were significantly higher in high proportion regions than in low proportion regions.