Explaining Japan's postwar longevity

After World War II, life expectancy at birth in Japan dramatically improved (Male: 50.1 years old in 1947, 67.7 in 1965, 74.8 in 1985,and 79.3 in 2008; Female: 54.0, 72.9, 80.5, and 86.1 respectively). We examined individual- and contextual-level theories of disease distribution and health behavior to explain these spectacular gains in life expectancy. Japanese trends in life expectancy gains can be divided into three time periods: 1945-65, 1965-85, and 1985-2010. In the immediate post-War period there were major declines in infant mortality and tuberculosis (1945-65). In the next period (1965-85), there were major declines in stroke mortality. Finally, in the most recent period (1985-2010) there were declines in all-cause mortality. We systematically reviewed articles on Japan's life expectancy and identified the theories/models used explicitly and/or implicitly in each article. We found spread of antibiotic drugs and better healthcare devices use during the first period. In the second period, public health campaigns such as sodium intake reduction (associated with the widespread use of refrigerators) could account for stroke mortality. Finally, in the most recent period, multiple individual- and contextual-level factors (including equitably distributed economic growth and social cohesion) likely contributed to the improvement of all-cause mortality. In sum, political economy of health, ecosocial theory, and diffusion of innovations theory fit well with the trends described above. Our analysis implies that theories addressing spatiotemporal scales at multiple levels can be more useful than individual-level theories of mortality change.