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Chapter 4: Mortality, 2010-based NPP Reference Volume This product is designated as National Statistics

Released: 29 March 2012 Download PDF

Past trends in life expectancy

During the 20th century, the UK witnessed a continuation of the pattern of falling mortality rates that began around the 19th century. Over these two centuries there has been a change in the pattern of mortality, from high infant and child mortality driven by the prevalence of acute and infectious diseases, to a new pattern in which adult mortality dominates, and chronic and degenerative diseases are now the most common causes of death. The pattern has been broadly similar in England, Scotland, Wales and Northern Ireland. 2,3,4

One measure of the mortality rates in a particular year is the period expectation of life at birth, which is the average number of years a new-born baby would live for, based on the mortality rates for the given year. Figure 4.1 shows that there was a fairly steady increase in this measure throughout the 20th century and continuing into the 21st century. However, progress was slower between 1950 and 1965, particularly for males, and until 1950, epidemics and severe winters caused significantly higher mortality rates in some years.  

Figure 4.1: Period expectation of life at birth according to mortality rates experienced in given years, 1911 - 2010, United Kingdom

Period expectation of life at birth according to mortality rates experienced in given years, 1911 - 2010, United Kingdom
Source: Office for National Statistics

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Much of the increase in the period expectation of life at birth in the first half of the 20th century can be attributed to the reduction of infant and child mortality to very low levels by about 1950. Infant and child mortality rates have now fallen to such low levels that further reductions can have little effect on the expectation of life at birth, which has thus come closer to being a measure of the normal life span. Since about 1940, the increasing control of infectious diseases has considerably reduced the number of early adult deaths, and there has recently been a reduction in the number of those dying early from circulatory diseases.2,3,4 The greatest decline in mortality rates at advanced ages has occurred since the 1970s. However, in general, mortality rates at the oldest ages declined less over the 20th century in relative terms than those at younger ages.

Figure 4.2 shows that period life expectancy at age 65 has also risen during the 20th century and continues to rise in the 21st century. For females, the annual increase was relatively constant over this period whereas for males, after an initial period of increasing longevity, period life expectancy at 65 remained almost constant between 1940 and 1970. Since 1970 there has been a rapid decline in mortality rates at advanced ages, particularly for males for whom mortality is currently improving more rapidly than female mortality. As a result, the age differential in period life expectancy at age 65 between males and females has reduced from around 4.0 years during the 1970s and early 1980s to 2.6 years in 2010.  A partial explanation for this may be the different historical patterns in cigarette smoking between men and women, with a higher proportion of males smoking in the past than females and the peak consumption for males being earlier (1940–1960) than for females (around 1960). 5,6 This might suggest that the rate of increase in female expectation of life at 65 will continue to be slower than for males over the next few years. 

Figure 4.2: Period expectation of life at age 65 according to mortality rates experienced in given years, 1911 - 2010, United Kingdom

Period expectation of life at age 65 according to mortality rates experienced in given years, 1911 - 2010, United Kingdom
Source: Office for National Statistics

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In many contexts it is more meaningful to calculate the expected average lifetime taking into account known or assumed improvements in mortality rates in the future (such expectations of life are often referred to as ‘cohort’ expectations of life).  Cohort life expectancies are discussed in greater detail later in this chapter.

A number of publications provide reviews of long-term mortality trends in the UK.1,2,3,4,7,8,9

Future prospects for life expectancy

Since the 1980s the period expectation of life at birth in the UK for females has increased by about 1.9 years per decade, while male life expectancy has increased by around 2.6 years per decade.  However, there are diverse opinions amongst demographers as to the level of longevity that might reasonably be expected in the future.9,10,11,12 One can point to Japan, where the period expectation of life at birth in 2010 was about 86.4 years for females and 79.6 years for males,13 and to other countries in Europe, such as Italy, Norway, Sweden and Switzerland, which also currently have higher period expectations of life at birth than the UK for both males and females.14 There is also the possibility of lower incidences of cancer, heart disease and strokes through changes in lifestyle and, through medical advances, greater control of these when they do occur. In particular, mortality rates for heart disease and strokes have fallen quite rapidly and steadily over the 1990s for males and females aged 40 to 64 and to a lesser extent for older men and women.15 Since 2000, the falls in mortality rates from these causes have continued at around the same pace for the 40–64 age-group and have accelerated for older men and women (aged 65 and over). Mortality rates from circulatory diseases had fallen to similar levels as the all cancers mortality rate by 2008. In the future, changes in mortality rates from causes other than circulatory diseases will have an increasingly greater effect on the rates of future mortality improvements.

On the other hand some demographers believe that, despite the possibility of advances in medical practices and of encouraging healthy lifestyles, a law of diminishing returns will apply to mortality rate reductions at advanced ages, partly because no more than a minority of the population will adopt truly healthy lifestyles. It is also possible that new diseases, or the re-emergence of existing diseases such as tuberculosis, may serve to temper future improvements in mortality.

Methodology and derivation of UK base mortality rates

Rather than focusing directly on expectations of life in formulating the mortality assumptions for population projections, the prospects for mortality rates at different ages, and for different generations, have been considered separately. In this chapter, the assumptions for the projections are given in the form of central mortality rates (mx ). The difference between these and the probabilities of dying (qx ) used to carry out the actual projections is described under methodology in chapter 1.  The latter figures can be accessed via the NPP interactive table download tool by selecting assumed age specific mortality rates.

Mortality rates for the UK in each calendar year in the period 1961 to 2009 have been smoothed to remove fluctuations from age to age and year to year, using a new methodology. Crude mortality rates were calculated using deaths data and mid-year population estimates for 1961 to 2009 (deaths data for 2010 did not become available until after the mortality assumptions for these projections were finalised). Population estimates by age for those aged 90 and over from 1979 onwards (and retrospective estimates for earlier years, back to when these persons were aged 80) were calculated using the Kannisto-Thatcher survivor ratio method which is a modified form of the method of extinct generations.16 The retrospective estimates to age 80 have been found to give more reliable results than using the official population estimates made at the time.

A p-spline model was then applied to the resulting crude mortality rates to produce a fitted, smoothed mortality surface to the historical data for each gender.17 The addition of an extra year’s data or extending the age range can result in quite different rates of improvement at some ages for the most recent years’- in the data used (often termed ‘edge effects’).  This was the case for the methodology previously used to smooth historical data. Comparisons of the results using different ranges of calendar years and ages were made to assess how sensitive improvement rates calculated from the smoothed mortality rates for a given year were to these edge effects.

It was found that adding an extra year’s data often altered the improvement rates derived for previous years for some ages.  In particular, when an extra year's data are added improvements calculated for the final and penultimate years of the data range tend to be altered more than those for earlier years, which were usually not altered to a significant degree.  The results suggest that improvements for the second last and earlier years should not alter very much when data for an additional year are added. 

As a result of these analyses, smoothed mortality rates were calculated using data for years 1961 to 2009 and age ranges 0 to 100 for males and 0 to 105 for females.  Age-specific rates of mortality improvement were then calculated for the year 2007 using the smoothed mortality rates calculated for 2006 and 2007.  These mortality improvement rates for 2007 were then projected forward to 2010 by assuming that the same rates of improvement applied in 2008, 2009 and 2010. This projection was carried out by year of age for those born in 1960 and later and by cohort for those born before 1960.  Improvement rates in 2010 for ages where this methodology did not give an assumed rate were obtained by interpolation from ages where rates were thus derived.

Assumed age specific base mortality rates for 2010 were obtained by applying the resulting assumed rates of improvement to the smoothed age-specific mortality rates produced for 2007.

Base mortality rates for individual countries  

Base mortality rates for the calendar year 2010 were initially calculated for the UK, as described above. Base mortality rates for the four individual countries of the UK were obtained by adjusting the UK figure at each age in proportion to the particular country’s experience relative to the UK in the three years 2007 to 2009. These rates for individual countries are shown for selected ages in Table 4.1. The mortality improvement factors described later in this chapter were then applied to the projected base mortality rates for 2010 for each country to obtain the projected mortality rates for future years.

Table 4.1: Assumed base mortality rates (mx) per 100,000 by selected ages, 2010

Males   Females
England Wales Scotland Northern Ireland   England Wales Scotland Northern Ireland
  0 500 498 458 500   415 371 392 445
  2 16 13 15 16   14 14 14 13
12 12 13 13 18   9 12 10 9
22 60 73 95 97   25 23 36 30
32 95 130 171 107   46 56 65 47
42 179 209 267 220   107 123 142 115
52 398 435 538 439   267 287 344 298
62 968 1,012 1,293 1,113   630 725 829 643
72 2,546 2,777 3,206 2,724   1,640 1,853 2,119 1,724
82 7,699 7,987 8,821 8,477   5,511 5,690 6,529 5,621
92 20,019 21,539 21,089 22,556   17,844 18,414 19,085 19,582
102 48,468 46,378 48,468 54,639   44,745 44,827 46,484 45,929

Table source: Office for National Statistics

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National Statistics quality review

A review of the methodology for projecting mortality rates in the national population projections for the UK and constituent countries, carried out under the National Statistics Quality Assurance programme, was published in December 2001.18 The main object of the review was to assess whether the methodology used for projecting mortality rates in the national population projections met the needs of the wide range of users of the projections, met best practices and was founded on good basic data. The review concluded that none of the alternative methodologies assessed would be likely to outperform the methodology used for projections during the 1990s and that the existing methodology should be retained. However, the assumed values for the key parameters used would be reviewed for each new projection round. A number of recommendations for improving the methodology were made in the review and these have been incorporated in recent projections.

Effect of assumptions

The implications of these assumptions in terms of the period expectation of life at birth are shown in Figure 4.4 and Table 4.4Figure 4.5 shows the implications for period expectations of life at age 65.  As can be seen from Table 4.4, the actual period expectations of life at birth in the UK in 2010 for males was higher (and for females the same as) than the underlying trend figures.

Figure 4.4: Actual and projected period expectation of life at birth according to mortality rates for given year, 1981-2085, United Kingdom

Actual and projected period expectation of life at birth according to mortality rates for given year, 1981-2085, United Kingdom
Source: Office for National Statistics

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Figure 4.5: Actual and projected period expectation of life at age 65 according to mortality rates for given year, 1981-2085, United Kingdom

Actual and projected period expectation of life at age 65 according to mortality rates for given year, 1981-2085, United Kingdom
Source: Office for National Statistics

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In 2035, period expectation of life at birth for the UK is around 0.1 years lower than in the previous projections for males and 0.2 years lower for females compared to the previous projections. These differences are mainly due to the age-specific mortality rates for 2010 being assumed to be higher and the rates of mortality improvement between 2010 and 2011 assumed to be lower at many ages below 90 compared to those projected for the same period in the 2008-based projections. Over the early years of the projections these counterbalance the assumption of higher rates of mortality improvement at most ages in 2035.

Table 4.4 also gives ratios of standardised mortality rates for selected future years, together with comparable figures for some past years. The standardised mortality rate is the overall mortality rate (that is, total number of deaths divided by total population) resulting from applying the age-specific mortality rates for a particular year to the population numbers for a standard year, taken here as the year 2001. The ratio of these overall mortality rates for selected years to that for a standard year (the average of three years, 2000–2002, in this case) is given in the table. This measure is sometimes called the comparative mortality figure and details of this index decomposed into age-group indices have been published for the UK.22 

Table 4.4: Actual and projected period expectation of life at birth according to mortality rates for the given year, and ratios of standardised mortality rates, 1981–2071, United Kingdom

Period expectation of life at birth  (years) Ratios of standardised mortality rates (2000–2002 = 1.00)
Males Females Males Females
Actual
1981 70.9 76.9 1.47 1.30
1986 71.9 77.7 1.38 1.23
1991 73.1 78.6 1.25 1.14
1996 74.2 79.4 1.14 1.09
2001 75.7 80.4 0.99 0.99
2006 77.2 81.5 0.86 0.89
2010 (actual rates) 78.5 82.4 0.77 0.82
2010 (trend rates) 78.3 82.4 0.77 0.82
Projected
2011 78.6 82.6 0.75 0.80
2021 81.0 84.7 0.59 0.63
2031 82.8 86.5 0.51 0.53
2035 83.4 87.0 0.48 0.50
Longer-term projections
2041 84.2 87.8 0.45 0.46
2051 85.6 89.0 0.40 0.41
2061 86.9 90.2 0.35 0.36
2071 88.3 91.4 0.31 0.32

Table source: Office for National Statistics

Table notes:

  1. Standardised on 2001 population estimates

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Expectation of life for generations

So far in this report, expectations of life have mainly been calculated on the basis of the mortality rates for a particular calendar year (period life expectancies). However, for some purposes, cohort life expectancies, which allow for future known or assumed changes in mortality, are more appropriate measures. Further information on the difference between period and cohort life expectancies is available on the ONS website.23 Table 4.5 shows projected period and cohort expectations of life at selected ages for four different years.

Table 4.5 shows that the projected period expectation of life at birth for a male in the UK was 78.5 years on the basis of the mortality rates for 2010. However, taking into account assumed mortality improvements in later years, a male born in that year would be expected to live for 90.2 years. Similarly, the average man aged 65 in 2010 would live for a further 18.1 years based on the mortality rates for 2010. However, taking account of the assumed further mortality improvement after 2010, he would actually be expected to live for a further 21.0 years.

Table 4.5: Period and cohort expectation of life by selected ages for the years 2010, 2011, 2021, 2031 and 2035

United Kingdom

Males Females
2010 2011 2021 2031 2035 2010 2011 2021 2031 2035
Period expectation of life
  0 78.5 78.6 81.0 82.8 83.4   82.4 82.6 84.7 86.5 87.0
15 63.9 64.1 66.5 68.2 68.7   67.9 68.1 70.1 71.8 72.3
60 22.1 22.3 24.4 25.8 26.3   24.9 25.1 27.0 28.5 29.0
65 18.1 18.3 20.3 21.7 22.1 20.7 20.9 22.7 24.1 24.6
75 11.1 11.3 13.1 14.3 14.6 12.9 13.1 14.7 16.0 16.4
85 6.0 6.1 7.3 8.4 8.7 6.9 6.9 8.1 9.2 9.5
Cohort expectation of life
  0 90.2 90.3 92.0 93.5 94.2 93.7 93.8 95.2 96.6 97.2
15 73.4 73.6 75.2 76.7 77.3 77.1 77.3 78.6 80.0 80.6
60 25.5 25.6 26.9 28.2 28.7 28.5 28.6 29.8 31.0 31.5
65 21.0 21.1 22.4 23.5 24.0 23.7 23.8 25.0 26.1 26.6
75 12.8 13.0 14.3 15.3 15.6 14.7 14.9 16.2 17.1 17.5
85 6.5 6.6 8.0 8.8 9.1 7.3 7.4 8.9 9.8 10.1

Table source: Office for National Statistics

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Figure 4.6 shows the cohort expectation of life at birth for England and Wales for generations born from 1850 to 2050, and Figure 4.7 shows the cohort expectation of life at age 65 for those reaching age 65 in 1850 to 2050 based on the actual mortality rates experienced in the past or assumed for the future. 

Figure 4.6: Cohort expectation of life at birth according to historic and projected mortality rates, persons born 1850–2050,England and Wales

Cohort expectation of life at birth according to historic and projected mortality rates, persons born 1850–2050,England and Wales
Source: Office for National Statistics

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Figure 4.7: Cohort expectation of life at age 65 according to historic and projected mortality rates, persons who reached age 65 1850–2050, England and Wales

Cohort expectation of life at age 65 according to historic and projected mortality rates, persons who reached age 65 1850–2050, England and Wales
Source: Office for National Statistics

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About half of the increase in cohort life expectancies at birth between generations born in 1850 and 1945 was due to the reduction in infant and child mortality to very low levels. Subsequent generations have benefited particularly from the almost complete elimination of deaths from acute and infectious diseases. Figure 4.6 illustrates the point that, while current reductions in mortality rates at the older ages will continue to extend the average lifetime, once this reaches around 78 years for males and 83 years for females (that is, for men and women born in 1950), further progress is likely to be much slower. The great majority of deaths will then be attributable to chronic and degenerative diseases.

While the cohort expectation of life at age 65 for females has been increasing at a fairly steady rate since the 1930s, the cohort expectation of life at age 65 for males showed relatively little increase between 1930 and 1970 after which it began to increase more rapidly than for females. As discussed earlier, a partial explanation for this may be the different historical patterns in cigarette smoking between men and women. This is likely to have delayed mortality rates for older males falling to the levels they would have reached had they followed the reductions in female mortality rates experienced during the 1950s and 1960s, rather than indicating a continuing convergence of male mortality rates to those for females.

Constituent countries of the UK

In principle, a different rate of mortality improvement could have been employed for each country of the UK, perhaps showing a convergence later in the 21st century. However, as discussed earlier, a comparison of mortality improvements for each country with those experienced in the UK suggested that the same rates of mortality improvement by age and sex could be assumed for each country of the UK, except for Scotland, where different rates of improvement were assumed to 2035 for males and females at certain ages. The resulting projected mortality rates and expectations of life do vary between countries, of course, as shown in Table 4.6, because of the different starting mortality rates. Of the four countries, England shows the highest life expectancy and Scotland the lowest.

As can be seen from Table 4.6, compared with the 2008-based projections, period expectations of life at birth for males and females are lower in the early years of the projection period but are generally broadly similar by 2035. In 2035, period expectations of life at birth for males are projected to be broadly similar for England, 0.1 years lower for Wales, 0.2 years lower for Scotland and 0.1 years lower for Northern Ireland. The differences are slightly greater for females, with period life expectancies at birth around 0.1 years lower for England, 0.2 years lower for Wales, 0.3 years lower for Scotland and 0.2 years lower for Northern Ireland in 2035 compared to those previously projected.

Cohort life expectancies at birth for both males and females are projected to be higher than in the previous projections for each country of the UK for all years.  For those born in 2035 the differences are around 2.2 years higher for England, Wales and Scotland and 2.0 years higher for Northern Ireland.  For females the differentials are slightly smaller; 2.0 years higher for England, 1.9 years higher for Wales, 1.7 years higher for Scotland and 1.9 years higher for Northern Ireland.

Table 4.6: Period and cohort expectation of life at birth for the years 2010, 2011, 2021, 2031 and 2035

Corresponding results from the 2008-based projections are shown in italics

2010   2011   2021   2031   2035
Period expectation of life at birth          
Males                          
England 78.8 78.9   78.9 79.2   81.4 81.7   83.1 83.2   83.7 83.7
Wales 77.9 78.1   78.0 78.4   80.5 81.0   82.3 82.5   82.9 83.0
Scotland 76.2 76.2   76.2 76.5   78.5 78.9   80.3 80.5   80.9 81.0
Northern Ireland 77.1 77.6   77.6 77.9   80.1 80.5   81.8 82.1   82.4 82.5
United Kingdom 78.5 78.5   78.6 78.9   81.0 81.4   82.8 82.9   83.4 83.4
                         
Females                          
England 82.7 82.7   82.9 82.9   85.0 85.2   86.7 86.9   87.2 87.3
Wales 81.9 82.1   82.2 82.4   84.3 84.7   86.1 86.4   86.6 86.8
Scotland 80.6 80.7   80.8 81.0   82.9 83.3   84.6 85.0   85.2 85.5
Northern Ireland 81.7 82.2   82.1 82.4   84.4 84.7   86.1 86.4   86.6 86.8
United Kingdom 82.4 82.4   82.6 82.7   84.7 85.0   86.5 86.7   87.0 87.1
                         
Cohort expectation of life at birth                
Males                          
England 90.5 89.1   90.6 89.2   92.2 90.4   93.8 91.7   94.4 92.2
Wales 89.8 88.4   89.9 88.6   91.5 89.8   93.1 91.1   93.8 91.6
Scotland 87.8 86.5   87.9 86.6   89.6 88.0   91.3 89.3   92.0 89.8
Northern Ireland 88.9 87.9   89.2 88.0   90.8 89.3   92.4 90.6   93.1 91.1
United Kingdom 90.2 88.8   90.3 89.0   92.0 90.2   93.5 91.5   94.2 92.0
                         
Females                          
England 93.9 92.6   94.0 92.7   95.4 93.8   96.8 94.9   97.4 95.4
Wales 93.3 92.2   93.5 92.3   94.9 93.4   96.4 94.5   96.9 95.0
Scotland 92.0 90.9   92.1 91.0   93.6 92.2   95.1 93.4   95.6 93.9
Northern Ireland 93.1 92.1   93.4 92.2   94.8 93.3   96.2 94.5   96.8 94.9
United Kingdom 93.7 92.4   93.8 92.6   95.2 93.7   96.6 94.8   97.2 95.2

Table source: Office for National Statistics

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Mortality differences between males and females

In common with other Northern European countries,1 the excess of period life expectancy at birth for females over males rose in the UK during the period 1900 to 1970, before declining in more recent years. In the UK the differential has fallen from 6.0 years in 1980 to 3.9 years in 2010; it is projected to fall to about 3.6 years by 2035. This decline has been driven mainly as a result of changing differentials in mortality at older ages.  These are often driven in turn by changes in behavioural factors such as smoking.  For example, in recent years there has been an increasing incidence for women of lung cancer deaths, as compared with falling rates for men. In general, women took up smoking later than men and for them the peak of lung cancer deaths and other deaths related to smoking is still to come.5, 6

The changing life table

Figures 4.8 and 4.9 illustrate how the survival curve, which shows the proportion of those born in a given year who survive to each age, is progressively moving to the right of the chart, as more and more deaths occur at advanced ages. The charts are based on the average of male and female mortality in England and Wales. In Figure 4.8, the survival curves are calculated on a period basis and show the percentages who would survive to successive ages if they experienced the mortality rates of the year shown with no allowance for known or projected changes in mortality rates for the years thereafter. The first, least rectangular, curve represents the life table according to the mortality rates of the year 1851 and successive curves are given at 20 year intervals, with the uppermost being the projected life table for the year 2031. From this chart it can be seen that the median age at death, that is, the age to which half of those born survive, was about 45 on the basis of the mortality rates of 1851; this is projected to increase to about age 88 by the year 2031.

Figure 4.9 shows the survival curves calculated on a cohort basis, that is, allowing for known and projected future changes in mortality after the cohort’s year of birth. Since mortality rates have, in general, been improving over past years and are projected to continue to improve, the survival curve for a given year in Figure 4.9 lies to the right of that for the corresponding year in Figure 4.8.  From this chart it can be seen that, on a cohort basis, the median age at death for those born in 1851 was actually about 48, this is projected to be about 95 for those born now and to increase further to about age 98 for those born in 2031.

It is clear from Figure 4.8 that recent improvements in period expectation of life at birth have been due primarily to increases in survival to elderly ages. In contrast, increases in maximum lifespans have been comparatively small. There is limited scope for further reduction in mortality rates at young and middle ages. Any continuation of recent increases in expectation of life will only be achieved through major falls in mortality at older ages.

Further details

Projected numbers of deaths and comparisons with the previous (2008-based) projections are discussed in Chapter 2. While Chapter 6 presents the results of variant projections based on alternative assumptions about future mortality.  The detailed age specific rates assumed in the principal and variant projections for each country can be accessed via the NPP interactive table download tool.30

Figure 4.8: Proportion of persons surviving (on a period basis) to successive ages, according to mortality rates experienced or projected, persons born 1851-2031, England and Wales

Proportion of persons surviving (on a period basis) to successive ages, according to mortality rates experienced or projected, persons born 1851-2031, England and Wales

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Figure 4.9: Proportion of persons surviving (on a cohort basis) to successive ages, according to mortality rates experienced or projected, persons born 1851-2031, England and Wales

Proportion of persons surviving (on a cohort basis) to successive ages, according to mortality rates experienced or projected, persons born 1851-2031, England and Wales
Source: Office for National Statistics

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Views on future levels of mortality improvements and expectations of life

Mortality projections prepared in other countries and by other agencies tend to be based largely on extrapolation of past trends either in rates of mortality improvement or in expectations of life. Expert opinion is often used to inform the assumptions made. It is therefore perhaps helpful to summarise some of the current arguments put forward by experts regarding future levels of mortality improvements and life expectancy, for the UK and for other developed countries.

For the UK, several factors have been identified amongst the likely drivers of future mortality change including the ‘cohort effect’, the ‘ageing of mortality improvement’ (where the ages at which the highest rates of improvement have occurred have been increasing over time), increased uncertainty at younger ages, changes in prevalence of cigarette smoking, the effects of other lifestyle changes and medical advances. These are all discussed elsewhere in this chapter.

Appendix A of the Background and methodology report published on 26th October 2011 provides a note on the meeting of the National Population Projections Expert Advisory Group  at which members were asked their views on the validity of a large range of arguments which might be thought likely to influence future mortality trends. In general the UK experts felt that the current high rates of mortality improvement were likely to continue into the future. Many events were occurring which would increase the chances of longevity increasing such as continuing medical and bio-technological advances, more effective health care systems and better health information and changes in lifestyle behaviour. Society would be able and willing to afford new treatments. However, there were factors which would work in the opposite direction and not all sectors of the population may choose to adopt lifestyle behaviours leading to increasing longevity. The likely impact of obesity was discussed. It was agreed that there would be an increase in obesity levels and that this would have an effect on morbidity but there was less agreement as to the subsequent impact of this on mortality and whether any increase might be reversible in the medium-term. Some believed rising levels of obesity would lead to large downward influence on life expectancy but others believed the effect would be relatively small. 

It was acknowledged that there are elements influencing mortality improvement in both directions and that these need to be considered together to determine if the overall effect will be positive or negative. However, it was felt that those factors tending to increase longevity would outweigh negative influences and that the increase in life expectancy over the next 25 years would be similar to that experienced over the preceding 25 years.

There is currently a wide range of opinion amongst demographers, gerontologists, epidemiologists, academics and others as to the likely future pattern of longevity. Proponents of a biological maximal length to life refer to the ‘Hayflick’ limit – in the 1960s, Hayflick found that certain mammal cells could only divide up to a specific limited number of times, which were roughly linked with the typical lifespans of the organisms involved.24 Others have argued that lifespan can be viewed as a kind of biological warranty period linked to the reproductive period with physiological decline in the post-reproductive period producing restraints on the duration of life.25

Oeppen and Vaupel have observed that past predictions of limits to life expectancy have nearly all been broken afterwards.12 They have noted that record life expectancy (the highest life expectancy observed in any country of the world at any particular time) has increased at a steady pace over the last 160 years or so and suggest that this is likely to continue into the future. However, Olshansky11 and others have argued that there will be countervailing trends to the high rates of mortality improvements seen in recent years, driven by increasing levels of obesity, sedentary behaviours and other adverse lifestyle factors.

Some scientists have suggested that medical advances could lead to engineered negligible senescence with radical consequences for future life expectancy. For instance, de Grey26 believes that there are only seven mechanisms for accumulating damage to the human body and that therapies for reducing or reversing all of these types of damage are currently foreseeable.  Given sufficient commitment and resources, the possibility of life expectancy of 150 years, or even longer, may be with us in the next 20 to 30 years.

Given this wide disparity of views as to the likely future course of longevity, users of the projections can gain some insight into the sensitivity of their results to the various views on future mortality by considering the high and low life expectancy variants (see variants chapter 6). However, these are intended to represent plausible alternative assumptions and are far from reflecting the extremes of thinking on future mortality.

Latest Eurostat and UN projections

In their latest (2010-based, convergence scenario) projections,27 Eurostat assume an increasing period life expectancy at birth for the UK, though the rate of increase declines over time. Eurostat’s assumptions were derived by estimating life expectancy and the corresponding mortality rates for a future year (the convergence year) using a version of the Lee Carter method applied to historical combined data for several EU countries. Life expectancies and mortality rates for intermediate years for a given country were then obtained by exponential interpolation from current fitted data for that country to the assumed rates in the convergence year, with improvements occurring at a slowing pace over time. The Eurostat projections of period expectations of life at birth for males and females for the UK are lower than those in the 2010-based national population projections produced by ONS.  The differentials for males continue to increase throughout the projection period; for females the differentials increase until around 2033 after which the differentials decline over time. 

Both the national UK projections and the Eurostat projections assume higher projected period expectations of life at birth for the UK than the current United Nations 2010 Revision.28

References

1.  Caselli G (1994). Long-term Trends in European Mortality. OPCS Series SMPS no. 56. HMSO: London.

2.  Griffiths C and Brock A. (2003). Twentieth Century Mortality Trends in England and Wales. Health Statistics Quarterly 18, pp 5 -17. Available at: www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/no--18--summer-2003/index.html

3.  General Register Office for Scotland (2011). Scotland’s Population 2010 – The Registrar General’s Annual review of Demographic Trends 156th Edition. GROS: Edinburgh. (The GROS is now the NRS) Available at: www.gro-scotland.gov.uk/statistics/at-a-glance/annrev/2010/index.html

4.  Northern Ireland Statistics and Research Agency (2011). Registrar General Northern Ireland Annual Report 2010.  NISRA: Belfast. Available at: www.nisra.gov.uk/demography/default.asp50.htm

5.  Gjonça A, Tomassini C, Toson B and Smallwood S (2005).Sex differences in mortality, a comparison of the UK and other developed countries. Health Statistics Quarterly 26, pp 6-16. Available at: www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/no--26--summer-2005/index.html

6.  Pampel F (2004). Forecasting sex differences in mortality in high income countries: the contributions of smoking prevalence. Working Paper Pop 2004-0002. Institute of Behavioural Science, University of Colorado. Available at: www.demographicresearch.org/volumes/vol13/18/

7.  Office for National Statistics (1997). The Health of Adult Britain 1841-1994, Volume 1. The Stationery Office: London.

8.  Willets R. (1999). Mortality in the next millennium. Staple Inn Actuarial Society: London.

9.  Willets R et al. (2004). Longevity in the 21st Century. Institute and Faculty of Actuaries.

10.  Tiljapurkar S, Li N and Boe C (2000). A universal pattern of mortality decline in the G7 countries. Nature Vol 405 pp 789-792. Available at: www.nature.com/nature/journal/v405/n6788/abs/405789a0.html

11.  Olshansky JS, Carnes BA and Désequelles A (2001). Prospects for Human Longevity. Science Vol 291 pp 1491-1492. Available at: www.sciencemag.org/content/291/5508/1491.short

12.  Oeppen J and Vaupel J (2002) Broken Limits to Life Expectancy. Science Vol 296 pp 1029-1031. Available at: www.sciencemag.org/content/296/5570/1029.summary

13.  Ministry of Health, Labour and Welfare (2011). Abridged Life Tables for Japan 2010. Statistics and Information Department: Tokyo.

14.  Life expectancy at birth by gender for EU countries: epp.eurostat.ec.europa.eu/tgm/table.do tab=table&init=1&language=en&pcode=tps00025&plugin=1Eurostat-Tables,Graphs and Maps Life expectancy at birth, by gender

15.  Office for National Statistics (2006). Griffiths C and Brock A, Chapter 13, Focus on Health. Palgrave Macmillan: Basingstoke.

16.  Thatcher AR, Kannisto V and Andreev K (2002). The survivor ratio method for estimating numbers at high ages. Demography 6. Available at: www.demographic-research.org/volumes/vol6/1/

17.  Currie. D., Durban, M. and Eilers, P. H. C. (2004) Smoothing and forecasting mortality rates Statistical Modelling, 4, 279-298.

18.  Office for National Statistics (2001). National Population Projections:Review of Methodology for Projecting Mortality:NSQR Series No8.

19.  Hickman M et al. (1999). Impact of HIV on adult (15-54) mortality in London 1979-96. Sex Transm Infect. Dec: 75(6), pp 385-8.

20.  Brock A and Griffiths C (2003). Trends in mortality of young adults 15-44 in England and Wales, 1961-2001. Health Statistics Quarterly 19, pp 22-31. Available at: www.ons.gov.uk/ons/rel/hsq/health-statistics-quarterly/no--19--autumn-2003/index.html

21.  Goldring S and Henretty N et al (2011) Mortality of the ‘Golden Generation’: what can the ONS Longtitudinal Study tell us? Population Trends nr 145, Autumn 2011, pp 1-30. Available at: www.ons.gov.uk/ons/rel/population-trends-rd/population-trends/no--145--autumn-2011/index.html

22.  Daykin CD and Gallop A (2006). The recent trend of mortality in the United Kingdom. British Actuarial Journal, 12 (I). Available at:  www.actuaries.org.uk/research-and-resources/eshop/products/54-british-actuarial-journal-volume-12-part-1

23.  Further information on the difference between period and cohort life expectancies is available at: www.ons.gov.uk/ons/guide-method/method-quality/specific/population-and-migration/demography/guide-to-period-and-cohort-life-expectancy/index.html

24.  Hayflick L and Moorhead P (1961). The Serial cultivation of human diploid cell strains. Experimental Cell Research 5, pp 585-621.

25.  Carnes B, Olshansky SJ and Grahn D (2003). Biological evidence for limits to the duration of life. Biogerontology 4(1), pp 31-45.

26.  De Grey ADNJ (2003). The foreseeability of real anti-ageing medicine: focussing the debate. Experimental Gerontology 38, pp 927-934. Available at: www.ncbi.nlm.nih.gov/pubmed/12954478

27.  EUROPOP2010: available at: http://epp.eurostat.ec.europa.eu/statistics_explained/index.php/Population_projections

28.  World Population Prospects: The 2010 Revision. United Nations (2011). Available at: http://esa.un.org/unpd/wpp/Documentation/publications.htm

Background notes

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