Life expectancy worries – in some places

In some countries, life expectancy improvements are now not just slowing down, but for some groups within national populations, stalling and even going backwards.  This post confirms New Zealand has fared better than Australia, and both are in a better position than Great Britain (GB).

This post looks at period life expectancy at birth.  This is not a measure for how long people might live (see here for why not) but is a handy summary of average mortality rates across all ages in one calendar year. If life expectancy goes up, that’s good news as an indicator of people living longer.

Life expectancy has been increasing in New Zealand and peer countries from 2000 to 2016 (PDF). The selected peers are the OECD countries with life expectancy more than New Zealand’s latest figure less one year – 19 countries for males and a further six for females.

The US doesn’t make this cut as its life expectancy is low. New Zealand is in the top half of the OECD, and Australia is consistently better. GB* bobs around but is almost always below both Australia and NZ.

The track of the lines depends to some extent on how the data is sourced.  Some countries, like New Zealand and Australia, have smooth lines because the data is smoothed before it is used.  Life expectancies for other countries, like GB’s, are calculated based on deaths in each year, and there can be significant year-on-year variation, especially for small populations.

In New Zealand and Australia the national statistical agencies produce the underlying tables from which life expectancies are calculated every three years. These tables may have a degree of smoothing of the numbers, and then annual life expectancies are estimated by smooth interpolating across the three years. In GB, and other European countries, life tables are produced every year according to the actual data in that year, so there is minimal smoothing in the annual life expectancy indicators.

For New Zealand and Australia, not surprisingly, the smoothed lines run close to a trend line simply fitted in a straight line using the method of least squares.  GB’s life expectancy criss-crosses its trend line more erratically (PDF).  

British researchers have concentrated on how GB’s life expectancy falls below its trend line in the most recent years of the period.  This is especially true if the trend line is taken to be that fitted to the data of 2000-2011, rather than the line fitted to the full period to 2016. The stalling of life expectancy gains from 2011 to 2016 pulled the full trend down and with hindsight the gains from 2008 to 2011 look exceptionally good.

In both New Zealand and Australia similar stories play out but appear less dramatic because of the tight fit of trend (PDF). Still, life expectancy was above trend for an early period (around 2003-2008) and falls below for the latest couple of years.  You could see this as a suspicion of life expectancy gains now stalling.

In all three countries the rate of improvement of life expectancy has been lower recently.  The slopes of the trend line for each country for the whole, and the two halves, of the period are all positive, consistent with life expectancy increasing as a long-term trend, but lower for the second half than the first (PDF).

The slowing of the rate of life expectancy gains is confirmed as a bigger problem in GB than in New Zealand or Australia. In the second half of the period the rate of increase was only 50 per cent of what it what was for the first half for males in GB and Australia, while it was 60 per cent of the first half for New Zealand males.  For females, the rate of increase in the second half was 33 per cent of what is was in GB, 44 per cent in Australia but still 60 per cent in New Zealand.

The stalling of life expectancy improvement in recent years has adjusted long-term trend lines down. The life expectancy in 2016 expected on the long-term trend is lower than the life expectancy in 2016 predicted by extrapolating the trend line that would have been fitted using data of 2000-2008.  These downward forecast adjustments are shown here, in months.

Downwards forecast change, in months, for life expectancy at birth in 2016, using trend of 2000-8 instead of trend 2000-2016
Male Female
Australia 6.2 5.1
New Zealand 5.1 3.3
Great Britain 6.4 6.9

 

This confirms that life expectancy in New Zealand has fared better than in both Australia and GB. The problem in GB shows as slightly worse for females than males in terms of downward forecast adjustments (6.9 versus 6.4 months) but life expectancy is higher for women and the percentage loss is about the same.

In New Zealand, the downwards adjustment is larger for men – which was foreshadowed by this post on what was happening in the underlying mortality rates.

As new actual life expectancy data becomes available, these trends will become clearer. The first signs of a stalling in New Zealand may appear more strongly in the next release of life expectancy data.  But this analysis confirms other research suggesting that GB is in the grip of a concerning trend which may not have huge impacts on a national level, but is not happening to the same extent in other countries.

 

* Data is from OECD which uses Great Britain (England, Wales and Scotland) not United Kingdom.

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