The life expectancy of Americans has failed to keep pace with the increases seen in many other developed countries, despite rapid increases in spending on healthcare.

The effect is so striking that versions of this chart have gained a lot of traction on the web and social media recently. And rightly so: it sheds light on how the US has taken a different path.

FT Data has been observing this pattern in the past few weeks, even scrutinising the impact of high of drug prices.

Yet looking at country averages, which are essential to make international comparisons, has the effect of omitting a big part of the US story. Inequality means that individuals in the US have very different experiences in terms of both longevity and spending on health.

For example, some groups in the US — the poor and middle-class women — have actually seen a decrease in life expectancy during the past three decades.

When it comes to spending on healthcare, it is a similar story.

There is enormous inequality in the US: the bottom 50 per cent accounts for less than 3 per cent of overall spending on healthcare. The highest spending 5 per cent account for half of all health spending.

Looking at these figures, it is maybe easy to see why life expectancy has risen for the richest but stalled for the poorest.

But should we even assume that increased spending on healthcare always leads to increased life expectancy?

In fact, life expectancy is also greatly affected by preventable circumstances such as obesity, smoking, blood pressure and elevated blood glucose levels.

Obesity is far more prevalent in the US than in other OECD countries. This factor alone goes a long way towards explaining why Americans’ life expectancy has not kept up with their neighbours in developing countries.

American men lose 4.9 years of their life and women lose 4.1 due to preventable risk factors, according to a 2010 study by the Harvard School of Public Health.

If each individual risk factor was mitigated, there would be striking potential gains in life expectancy according to the study.

A person’s ethnicity and where they live in the US is also a predictor of both life expectancy and how healthy a person is, the research suggests.

There are in fact “Eight Americas” according to a previous socio-demographic study at Harvard University. This highlights how misleading it can be to think of the US in terms of simple national averages.

