May 09
Correlation is not causation, but it sure is a hint

In March I wrote about how projected life expectancies have fallen for the second year in a row. Since then, the story of falling life expectancies has garnered a lot of media attention. Jeremy Corbyn himself even pointed to waning life expectancies to demonstrate that the Conservative party is “running our country down” (although he may have misinterpreted the data slightly). Corbyn’s data mishap notwithstanding, several longevity experts have posited the theory that economic austerity is tied to falling life expectancy projections in some way. 

When the Conservatives were in power from 1979 to 1997, the average increase in NHS expenditure was circa 3% per annum and the average annual increase in life expectancy was 0.8%. Under the Labour government of 1997 to 2010, the average annual increase in NHS expenditure rose to around 6% and the average annual increase in life expectancy was up to around 1.2%. Under the coalition government of 2010 to 2015, annual increases in NHS expenditure were around 1% and the average annual increase in life expectancy has been close to 0.3%. The relative movements in NHS expenditure and life expectancy are illustrated well in the graph below.

LE - NHS  - graph.jpg
Source: Richard Willets, IFS, ONS

Correlation, however strong, is not causation. Cum hoc ergo propter hoc. Still, it is not something we can (nor should) ignore. Indeed, it would be surprising if NHS expenditure were not tied to life expectancy in some way. It makes sense that if more is spent on healthcare, people should live longer.

However, this is a very difficult thing to actually measure: the drivers of mortality improvements are wide ranging and complicated. Both NHS expenditure and mortality improvements are also strongly tied to wealth and the general state of the economy. A wealthier society makes healthier lifestyle choices and tend to live longer. A wealthier society is also associated with a flourishing economy which is likely accompanied by higher expenditure on the NHS. It is hard to separate out and quantify the effects of these two factors. 

There are also factors for which we have more concrete evidence. Circulatory disease was the major contributor to the immense mortality improvements observed in the 1990s and 2000s. Improvements from this cause have stalled since 2010. Some of this may well have been driven by NHS expenditure but we also know that the reduction in smoking has been crucial. It may just be that improvements from smoking cessation are now close to exhausted and this is the major driving force. 

It would be a truly immense project to fully pick apart the links between NHS expenditure and life expectancy. And this is a project that I doubt there is much appetite for at the moment. The results of such an analysis are likely to be unpalatable: either austerity is leading to falling life expectancies or putting more money into the NHS does not necessarily improve longevity. Perhaps a year of lowering life expectancies in 2017 (as currently looks likely to be the case based on ONS weekly death data) and the accompanying media furore will provide the necessary motivation.

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