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Mortality Assumptions

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There is a general consensus internationally among demographers that improvements in life expectancy will continue for the foreseeable future.  The main question to be addressed therefore by the Expert Group is the rate of improvement. 

The Expert Group are indebted to Ms Rabia Naqvi and Dr Shane Whelan (FSAI) of UCD School of Mathematics and Statistics and Dr Mary Hall (FSAI) of DCU School of Mathematical Sciences for their input and expert guidance with regards to the mortality part of the projections work.

The agreed mortality assumptions are outlined in the summary table below.  Ireland's historical mortality trends and the methodology underpinning these assumptions are also outlined in this chapter.

Mortality Assumptions Agreed

Mortality rates for males and females are assumed to improve at 2.5% and 2.0% per annum respectively in the short-term.

The long-term rate of improvement is assumed to be 1.5% per annum (unchanged since the last report).  The short-term rate declines linearly over a 25 year period to the long-term rate.

These rates are assumed to apply to all ages up to age 90.

These assumptions will result in gains in life expectancy from:

- 79.3 years in 2015 to 85.6 years in 2051 for males
- 83.3 years in 2015 to 88.3 years in 2051 for females

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Ireland has witnessed significant improvements in mortality since the start of the 20th century with male life expectancy increasing from 57.4 years in 1926 to 79.3 years in 2015 (a gain of 21.9 years), while females have seen a gain of 25.4 years (from 57.9 to 83.3). The biggest gains in both male and female life expectancy were recorded in the immediate post-war period, i.e. 1946 - 1961. These resulted from improvements in living conditions, as well as from advances in maternity services and medical treatment, such as immunisation.  See tables 5.1 and 5.2.

Show Table: Table 5.1 Gains in life expectancy at various ages 1926 - 2015

From the latter half of the 20th century, increases in life expectancy have been led by rapid reductions in adult mortality, particularly for males. Between 1991 and 2015 life expectancy at birth increased by 7.0 years for males while the increase for females over the same period was 5.4 years. The improvements have been most notable in the older age groups. Improved living conditions coupled with further developments in medical care are considered to be the main contributing factors.

The gap between male and female life expectancy is also continuing to decline.  A woman born in 1981 was expected to live 5.5 years longer than a man born in the same year.  By 2015 the gap in male and female life expectancies was estimated to have fallen to 4.0 years.

Show Table: Table 5.2 Life expectancy at various ages classified by sex, 1926 - 2015

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As in the previous projections, the mortality rates used in this exercise were projected using a ‘targeting’ approach.  This approach involves estimating the current rate of improvement for each sex and assuming that this rate of improvement will decline over a twenty-five year period to a long-term average improvement rate not dissimilar to the rates observed in the long-term past.

Estimating the current rate of improvement in mortality

A graduated life table was prepared for 2014-2016 following the same methodology as that employed for the previous projections exercise. Comparing these recent mortality rates with those of the last published Irish Life Table (ILT 16 centred on the year 2011) gave the average rate of improvement per annum over the period 2011 to 2015.

Analysis of these results showed a slowing of mortality improvements for both males and females. This analysis also suggested that male mortality rates were declining at a faster rate than their female counterparts.  The group agreed that the 2016 - 2051 projections be compiled assuming current trends of 2.5% per annum declines in mortality rates for males and 2.0% per annum for females. This entails a 0.5% reduction in the trend rate used in the 2013 projections for both sexes.  Applying these rates of improvement not only reflects current trends but would also preserve the gender differential in life expectancy within historic limits.

A zero per cent improvement (i.e. no improvement) was assumed for ages of 100 years and over.  For ages 91 years to 99 years, the current rate of improvement was estimated by linear interpolation between the assumed rate of improvement at age 90 years (2.5% for males and 2.0% for females) and the zero per cent rate of improvement at age 100 years.

Projecting mortality improvements between 2016 and 2040

As explained above, the projection methodology estimated the current average rate of mortality decline for the period 2011 to 2015 for each sex at each age.  For all years between 2016 and 2040, the mortality declines for that year at each age is a simple linear interpolation between the decline in 2016 and the assumed rate in 2040. For ages of 100 years and over, no improvements were assumed either now or in the future, while for ages between 90 years and 100 years, the rates of mortality decline were estimated by linear interpolation between the assumed rate at age 90 and 0% improvement at 100 years of age.

Projecting mortality improvements from 2041 onwards

The Expert Group decided that an annual decline of 1.5 per cent was appropriate to apply to both sexes up to age 90 years from 2041 onwards.  This rate of decline was also utilised in the previous projections exercise and is not dissimilar to the average rate of mortality decline over the long term past.  For age 91 years to age 99 years, the rate of improvement was estimated by linear interpolation between the assumed rate at age 90 and 0% improvement at age 100 years.  For ages of 100 years and over, no further mortality improvements are assumed.


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Under the agreed assumptions male life expectancy in 2051 is projected to be 85.6, a gain of 6.3 years over the 36 year period (2015 – 2051).  For females there is a projected gain of 5 years to 88.3.   The gap between male and female life expectancy is projected to reduce to 2.7 years by 2051. See table 5.3 and fig 5.1.


Show Table: Table 5.3 Projected life expectancy at various ages classified by sex, 2021 - 2051

X-axis labelMaleFemale

While this report contains a number of summary tables, detailed results of the population projections from 2017 to 2051 are available on the CSO Statbank here.

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