Recent mortality improvement trends in the UK

Figure 1 displays the crude mortality rates (on the logarithmic scale) for women in the UK for selected ages from calendar year 1965 to 2016. This shows a steady decline of mortality rates over time, albeit some year-to-year fluctuations.

The data post-2010 indicates that the reduction of mortality rates observed in earlier years could be slowing down over the most recent past (at least for some ages). Similar comments apply to the crude mortality rates for men (not shown).

Although some early patterns emerge from the crude mortality rates in Figure 1, they are obscured by fluctuations, especially at the youngest ages. More robust patterns can be obtained by aggregating data across ages, separately for males and females. The result in terms of standardised mortality rates for males and females is shown on the panel on the left-hand side of Figure 2; the resulting mortality improvement rates are shown on the right-hand side. A number of comments can be made from these graphics.

For example, they confirm the steady fall of mortality rates over time for men and women; in particular, male’s mortality rates have been falling faster than female’s (at least post-1980). Post-2010, the fall of mortality rates seem to have slowed down for both genders, and the trend has become almost at: we see this feature from both panels, noting, in the right hand panel, the dropping of the annual improvement rates down towards zero during the last five years of the time-period.

Table 1 presents a more detailed summary and comparison of average yearly mortality improvements for narrow age-bands over multiple time-periods for both genders. This shows that the average improvement rates vary across time-periods and age-bands.

The Table also shows that mortality improvement rates post-2010 have slowed down compared to the previous decade. This applies essentially to all age groups if we compare 2001-2010 to 2011-16, for both men and women. But the gap difference between the two periods (i.e. before and after 2010) varies considerably across age groups.

The exploration carried out so far has been in terms of mortality rates and resulting improvements. Alternative metrics were considered and the conclusion was consistent regarding the slowdown of mortality improvements in the UK post-2010.

For example, Figure 3 displays comparative mortality factors by gender relative to 1965. The smoothed lines were added by fitting one-dimensional P-splines to data up to 2010. The fitted lines were then projected past 2010 using a second order difference penalty. These graphics show that mortality experience post 2010 in the UK is heavier compared to what one could have anticipated based on 1965-2010 trends.

Further analysis using more advanced mortality forecasting models across multiple countries was also carried out. We shall report the results in upcoming posts.