Why are life expectancy gains stalling?

Is a slowdown of life expectancy gains really something to worry about, or is it only to be anticipated now that lives are so long?

Summary

  1. Average lifespans are still increasing, but not as fast as they have been.
  2. A slowdown in life expectancy is not necessarily a problem but it is a call to understand and act on specific public health issues
  3.  We still need to prepare for ageing societies, and consider the quality of life and health at older ages

For many decades, the developed world has been used to life expectancy gradually improving.  Much attention has been given to recent slowdowns in life expectancy improvements, or even life expectancy stalling or going backwards for some groups within national populations.

Life expectancy is an indicator based on the number of deaths at each age compared to the size of population – this is the “mortality rate” or “death rate”. Changes in life expectancy are a consequence of the rate of change in mortality improvements.  Life expectancy increases when mortality improves, that is, mortality rates fall.

Previous posts showed that mortality improvement in New Zealand had not slowed as dramatically as seen in other countries and that a slowdown in life expectancy gains was a bigger problem in Great Britain than in New Zealand or Australia.

Why mortality improvement might slow

To some extent a slowdown in mortality improvement should not be surprising. Mortality improved noticeably in 1980s-2000s because of specific public health and medical interventions: people gave up smoking; surgery and pharmacy innovations reduced the incidence and death risk from cardiovascular conditions. There is less gain to be had from these interventions now. As a result, there is now simply less death risk for medical science to work its magic on.

New Zealand data here is used to illustrate, but a similar picture applies in other developed countries:

  • Death rates are falling for each age group over age 50. Only for ages over 80 years are there now more than 30 deaths per 1,000 lives each year. In 1971, that was only the case below age 70*.
  • As a result of mortality improvement, death generally, and increasingly, happens at high ages. For example, 90 per cent of the female babies born in 1971 are estimated to survive to age 70; for the 2017 cohort the same estimate is to age 85**.

Mortality improvements might also have slowed for reasons which would be expected to have less effect in future. There are concerns that new public health interventions or medical innovations are not meeting demand, given changing risk factors. In part this is a concern about scientific innovation not being fast enough. For example, cancer and neurological conditions, now more prominent causes of death following the reduced impact of cardiovascular risk, have not seen significant recent transformative medical treatments, but this could change.

There are concerns that public health, medical and social care budgets may have been cut back too much following financial crises.  It is known what could be done to mitigate or prevent some factors underlying higher death risk, such as diabetes, obesity, poor housing, different usage of health services, or other socio-economic detriments. It would be expected that at some point political pressure would result in higher funding, with consequent positive effect on mortality rates.

Similarly, it would be hoped that the fast increase in death rates from opioid use and addiction particularly observed in the US and Canada can be reversed.

A short-term detriment to mortality is excess winter deaths, particularly among older people.  Influenza deaths can be unusually high in some years, particularly when virulent strains have not been included in the flu vaccine. European countries showed unusual spikes in the winters of 2014/15, 2016/17 and 2017/18.

The slowdown may also be partly attributable to one particular cohort. The super-healthy “golden cohort” born around 1930 in the UK have had enhanced mortality improvements throughout their life, but are now, naturally, diminishing in number. Their contribution to the average mortality improvement in the population is therefore reducing in the UK, and likely in other countries too.

Does a mortality improvement slowdown matter?

Where the stalling of average mortality improvement or average life expectancy is a logical outcome from the high life expectancies now being achieved, then the implications are minimal.  Some stability in forecasting of future average lifespans could, by reducing uncertainty, make individual pension- or life-planning easier.

Analysis of the drivers of change in mortality can show warning signs for increasing population health issues, including inequities.  Differences between mortality rates in different socio-economic groups are reflected in life expectancies, chances of surviving to old age, and infant mortality. For example, in England from 2001 to 2015, the death rates for the least deprived fifth of neighbourhoods compared to the most deprived were not only lower but also improved faster – increasing the socio-economic gap.  The same study identified that of the many factors including income, education, crime, health, housing, environment and unemployment, income deprivation is the strongest independent predictor of mortality rates.

Further analysis, up to 2017, shows no evidence that this socio-economic mortality gap is closing, although it might have stopped widening further. The stalling of mortality improvement rates in recent years happened across all socio-economic groups, but the already lower improvement rates in most deprived areas did not fall as much as those in the least deprived areas.

Even in the UK, different studies show different gradients of the life expectancy gap across socio-economic groups, for different time periods. The picture is different again in other countries. For example, although income is associated with life expectancy, the gap in life expectancy between high and low income groups has increased over decades in the US, but remained stable in Canada. The variation in trends seen in different countries and population groups over different timescales, with poor explanations of causes, means that future forecasting of mortality trends is uncertain.

However, for large pension funds, or insurers with annuity business, small changes in assumptions made for future forecasting of lifespans can make a multi-million dollar or pound difference to how much money needs to be set aside for future liabilities.  This means changes in assumptions about future life expectancy do make headlines.

Life expectancy is often used as an indicator of success, but as its progress slows, there are diminishing returns from seeking to extend life.  Attention shifts from lifespan to healthspan. How healthy people are in later life becomes a more important metric of success than ever-longer life expectancy.  The goal becomes to extend the period of life without health issues and minimise the period during which ill-health affects quality of life.

Finally, it is worth noting that a mortality slowdown may not be obvious by looking around a community. Even as mortality improvement slows or stalls, life expectancy is still increasing. On average, people are living longer. Generally speaking, an individual can expect to live longer than parents or grandparents. And there will still be increasing numbers of the very old, because of previous improvements in mortality going back many decades.

 

 

* From Stats NZ Age-specific death rates by sex, December years (total population) Downloaded 12 April 2019

** Author’s calculation from StatsNZ New Zealand cohort life tables (March 2019 update) incorporating future mortality rates projected using the median projection of the 2016-base National population projections (published October 2016).

 

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