Trends of gender gaps in life expectancy in Japan, 1947-2010: associations with gender mortality ratio and a social development index.

Aim: This study analyzed the trend of gender gaps in life expectancy (GGLE) in Japan between 1947 and 2010, and explored the correlations of GGLE with gender mortality ratio and social development indices.

Methods: Using GGLE and social indices data collected from the official websites, we carried out trends analysis of GGLE by calculating segmented average growth rates for different periods. We explored the association between GGLE and all-cause mortality; and between GGLE and Human Development Index (HDI) while controlling for time trend, by computing the generalized additive models based on the software R (version 2.15).

Results: Japan's GGLE increased in a fluctuating fashion. Across 53 years, the average growth rates varied widely: 0.14% (1947-1956), 1.43% (1956-1974), 1.06% (1974-2004) and -0.60% (2004-2010) (overall average 0.87%). The value of GGLE peaked to 7.00 years in 2004, and then has slowly declined (6.75 years in 2010). Age-adjusted all-cause gender mortality ratio had a statistically positive association with GGLE (P<0.01), whereas HDI was found to have no such association.

Conclusion: The increased trend of GGLE in Japan could be partly explained by increased disease-specific mortality ratios (male/female), especially those involving chronic bronchitis and emphysema, diseases of the liver, suicide and cancer. The recent decline of GGLE might imply that Japanese women have been catching up with the lifestyle of men, resulting in similar mortality patterns. This calls for gender-sensitive approaches to developing policies and programs that will help sustain healthy lifestyles to combat smoking and alcohol intake, and social support to prevent suicide.