Although Angus Deaton’s book The great escape: health, wealth and the origins of inequality was published in 2013, it is still being reviewed, and rightly so. It certainly deserves a wide audience. The seed for the book was sown in 2005, when Deaton reviewed The escape from hunger and premature death 1700-2100 by Robert Fogel, a Nobel Prize-winning economist. The theme of Deaton’s book, like that of Fogel’s, is the progress that has been achieved in diffusing health as well as prosperity across many societies in the world. Like Fogel, he wants to emphasize the magnitude of this achievement, which for Deaton involves an extended discussion of the measures that best capture progress. As the title makes plain, however, the book is not just a story about success. Deaton has written a great deal on the social determinants of health and the persistence of health inequalities within countries as well as between them, and these concerns are the obverse side of the story he wants to tell. His arguments support the increasingly mainstream view that inequalities in life span are perhaps the most fundamental form of inequality that exists among and between human populations. This means that life expectancy at birth acquires a critical importance as a metric for the achievement of both social justice and well-being.
One of Deaton’s reviewers, David Weil in the Journal of Economic Literature, highlights, as a central thread running through the book, questions about the significance and implications of the Preston curve. Samuel Preston published his much cited paper on the relationship between mortality and economic development in 1975. By fitting curves to diagrams which plot national data on GDP per capita against national data on life expectancy, he is able to make two important points about the relationship between them. Firstly, in the cross-sectional data the relationship is manifestly non-linear. Differences in life expectancy between low and middle income countries are highly sensitive to differences in GDP per capita. Among high income countries, however, the association between income and life expectancy is much weaker. The second point, which is really the central claim
The millennium Preston Curve from Deaton’s 2004 paper on Health in an age of Globalization
of Preston’s paper, concerns changes in the relationship over time. What the data he originally presented show – and the analysis has been updated several times subsequently - is that life expectancy gains occur at all income levels, which is another way of saying that the entire curve shifts upwards over time. Improvements in life expectancy can therefore be decomposed into two parts, an income effect and a non-income effect. Preston’s own analysis, which looks at the decades between 1930 and 1960, suggested that the income effect was considerably smaller (between 10% and 20%) than the non-income effect, which he ascribed to the global diffusion of medical and health technologies. As Deaton makes clear, the interpretation of the Preston Curve, particularly in regard to the claim about change over time (i.e. economic development and the health impact of gains in income), remains a live issue, and there is a batch of excellent commentaries on the curve in the International Journal of Epidemiology from 2007.
The Great escape also picks up and interweaves with his discussions of the Preston Curve a large and complex body of research and analysis stretching back to Thomas McKeown’s arguments about the limited contribution of therapeutic medicine to life expectancy gains in the twentieth century, and the social determinants of health. It is easy to show that rich countries have healthier populations than poor countries. Much of Sub-Saharan Africa is poor by any standards, and the region’s life expectancy at birth is now about one-third lower than it is in Northern Europe. A high degree of vulnerability to infectious and parasitic disease is strongly associated with poverty. The view that countries like the UK have only to look at their recent past to confirm this association is widely held. Poorer people had poorer diets and lived in conditions that increased their exposure to infectious disease. This line of argument, which was developed by McKeown in a series of papers and monographs from the ’50s to the ‘70s, was given a new lease of life by Robert Fogel.
Deaton takes a different view, at least when it comes to applying McKeown’s arguments to current international comparisons. That there is a relationship between income and health seems clear. The enormous disparities that can be found in both income and health, not only between countries, but also within them, are not independent of each other. It is no easy matter, however, to pin down the nature of the causal relationship between individual or household income and health, and this difficulty feeds through to efforts to prescribe policies that set out to remedy the situation. The ‘error’ which Deaton sets out to dispel is that “the diseases of poor countries are … ‘diseases of poverty’ in the sense that they will vanish if poverty is reduced, then direct health intervention may be less important than economic growth. (p106)”
About the Author
Kenneth Howse is a Senior Research Fellow at the Oxford Institute of Population Ageing. He is also a key member of The Collen Programme on Fertility, Education and the Environment.
Opinions of the blogger is their own and not endorsed by the Institute
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