Why Are We Lagging in Life Expectancy?
Life expectancy has been in the news lately. Over the summer, The New York Times summarized a new report from the CDC analyzing racial difference in life expectancy between U.S blacks and whites; last month, the OECD released comparative data between the U.S. and OECD countries; and Health Affairs ran a pair of articles in March (abstracts here and here ).
The CDC reports that U.S. life expectancy at birth increased by 11% from 1970 to 2010 (from 70.8 years to 78.7 years). Whites gained 10% in that period (71.7 years to 78.9 years) while blacks gained 17% (64.1 years to 75.1 years). Thus, the gap life expectancy between the white and black populations has decreased, from 7.6 years in 1970 to 3.8 years in 2010. But it’s still substantial.
The comparative data from the OECD put the U.S. life expectancy gains into perspective. The U.S., despite its gains, is losing ground internationally:
Most OECD countries have enjoyed large gains in life expectancy over the past decades. In the United States, life expectancy at birth increased by almost 9 years between 1960 and 2011, but this is less than the increase of over 15 years in Japan and over 11 years on average in OECD countries. As a result, while life expectancy in the United States used to be 1½ years above the OECD average in 1960, it is now, at 78.7 years in 2011, almost 1½ years below the average of 80.1 years. Switzerland, Japan, Italy and Spain are the OECD countries with the highest life expectancies, exceeding 82 years.
Right now, the U.S. ranks 51st in the world in life expectancy, according to the CIA’s World Factbook. The following graph shows that the U.S. was about at par with other OECD countries in the early 1990s, especially for females, but the other countries have created a big gap since.
So what’s going on here? Project Millennial recently drew attention to the widening gap in the probability of survival to age 50 for women; in the Health Affairs study, Jessica Ho of the University of Pennsylvania found that mortality differences below age 50 account for two-fifths of the gap in life expectancy at birth between American females and their counterparts in sixteen comparison countries. Among males, it accounts for two-thirds of the difference.
That tells us the relative contribution of certain demographics to the life expectancy gap, but doesn’t tell us why. There’s no shortage of suspects, given the known associations between life expectancy and income, education, race/ethnicity, smoking, obesity rates, and many others factors. A recent Institute of Medicine report noted that the disparities in life expectancy within the U.S. are even larger than the cross-national differences, and may help explain why the U.S. compares so unfavorably with peer nations.
But it is difficult to build a good regression model explaining these cross-national differences. My gut feeling is that the bottom 15% of the U.S. population (in terms of distribution) drags down the position of the U.S. in most international rankings - so that the main explanatory variable could be social inequalities, which are much larger in the U.S than in Europe. Unfortunately, this is difficult to prove, as most published national statistics are, by definition, country averages, and I would need the entire distribution to explore my ideas. But I'm still working on it and welcome your comments and suggestions below.