Commentary: The Preston Curve 30 years on: still sparking fires

Abstract

Samuel H Prestons classic paper The Changing Relation between Mortality and Level of Economic Development published in 1975 remains a cornerstone of both global public health policy and academic discussion of public health. Prestons paper illuminates two central stylized facts. The first is a strong positive relationship between national income levels and life expectancy in poorer countries though the relationship is non-linear as life expectancy levels in richer countries are less sensitive to variations in average income. The second is that the relationship is changing with life expectancy increasing over time at all income levels. Preston examined the relationship between life expectancy and income in three different decades: the 1900s 1930s and 1960s. In each decade the association between the two measures held true; more recent research shows that the income-life expectancy relationship still applies and continues to move upwards (although the AIDS epidemic in Sub-Saharan Africa has reduced life expectancy at the low end of the income scale in recent years). Although the basic facts set out by Preston are generally accepted there is still a great deal of dispute about the mechanisms that lie behind the relationships and the policy implications we can draw from them. (excerpt)