Life expectancy and disparity: an international comparison of life table data

Abstract

Objectives

To determine the contribution of progress in averting premature deaths to the increase in life expectancy and the decline in lifespan variation.

Design

International comparison of national life table data from the Human Mortality Database.

Setting

40 developed countries and regions, 1840–2009.

Population

Men and women of all ages.

Main outcome measure

We use two summary measures of mortality: life expectancy and life disparity. Life disparity is a measure of how much lifespans differ among individuals. We define a death as premature if postponing it to a later age would decrease life disparity.

Results

In 89 of the 170 years from 1840 to 2009, the country with the highest male life expectancy also had the lowest male life disparity. This was true in 86 years for female life expectancy and disparity. In all years, the top several life expectancy leaders were also the top life disparity leaders. Although only 38% of deaths were premature, fully 84% of the increase in life expectancy resulted from averting premature deaths. The reduction in life disparity resulted from reductions in early-life disparity, that is, disparity caused by premature deaths; late-life disparity levels remained roughly constant.

Conclusions

The countries that have been the most successful in averting premature deaths have consistently been the life expectancy leaders. Greater longevity and greater equality of individuals' lifespans are not incompatible goals. Countries can achieve both by reducing premature deaths.

Article summary

Article focus

• We examined the relationship between high life expectancy and low life disparity.

• We determined the relative importance of premature versus late deaths in increasing life expectancy and reducing life disparity.

• We examined whether policies to increase life expectancy were compatible with those to reduce lifespan variation.

Key messages

• Most of the gains in life expectancy are the result of reducing disparities in how long people live, by averting premature mortality.

• Progress in reducing death rates for people who live longer than average has had little effect on life disparity levels and has contributed only modestly to life expectancy gains.

• The countries that have been most successful at reducing premature mortality enjoy the highest life expectancies and the greatest equality in individuals' lifespans.

Strengths and limitations

• We are the first to examine this issue using a large, comparable database of 40 developed countries from 1840 to 2009 containing 7056 life tables.

• Our analysis was limited to countries with data of high enough quality to be included in the database.

• Although this database contains high mortality life tables from historic populations, it is unknown whether the patterns we observed would also be seen in contemporary emerging and developing countries.