We calculated age structure of long term elongation in life expectancy using Japanese life tables, mainly complete life tables and complementarily abridged life tables, examined quantitatively the role of medicine and public health.
The life expectancy of modern Japan has been achieved by nearly 50% before the 1950s in which anti-tuberculous drugs etc. are wide-spread, and achieved by 60% or more before the universal health insurance coverage and national health promotion projects, just as Thomas McKeown has pointed out, known as “McKeown Thesis”.
The rate of decrease in mortality rate and extension of life expectancy from before World War II until the middle of the 20th century has hardly changed after the spread of effective medical technology such as anti-tuberculosis drugs etc. This suggests that the mortality rate declined consistently from before and throughout World War II, and as well as the decrease in mortality rate and average life expectancy after the spread of effective medical technology such as anti-tuberculosis drugs etc. Thus, the decrease in the mortality rate and the extension of the life expectancy after the spread of effective medical technology, it was not much greater than the reduction of the mortality before the spread of medical technology.
Looking at these findings, the role of the modern medicine and public health after the mid-20th century should be, based on the mortality rate achieved before the mid-20th century, to maintain and to improve the level of mortality.