A chill wind

(Nov 27, 2015)

In a previous blogs I have looked at seasonal fluctuations in mortality, usually with lower mortality in summer and higher mortality in winter.  The subject of excess winter deaths is back in the news, as the UK experienced heavy mortality in the winter of 2014/15, as demonstrated in Figure 1.

Figure 1. Excess winter deaths in England & Wales. Source: ONS.

Excess mortality in England & Wales

Figure 1 shows some important features, but some are less immediately obvious than others.  The most obvious feature is that the winter of 2014/15 is indeed the worst for excess winter deaths for fifteen years.  Another obvious feature of Figure 1 is that it is the elderly who bear the overwhelming brunt of excess winter mortality.  However, there is an easily…

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Tags: season, influenza, winter, frailty, mortality plasticity

Mortality shocks

(Jan 30, 2009)

Mortality, and in particular rapidly improving mortality, has shot up the actuarial agenda in recent years. Actuaries have been caught by surprise not so much by the improvement (which has been happening steadily for over a hundred years now) but by the acceleration in the improvement. This accelerated improvement started around 1970 and shows no sign of running out of steam. The graph of mortality heads steadily south, albeit at an increasing speed.  The graph below illustrates the dramatic turn of events that took place around 1970 for Swedish males at age 70 (data from the Human Mortality Database):

Figure 1.  Log mortality for Swedish males aged 70

Mortality at age 70

However, other more spectacular changes in mortality are…

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Tags: Spanish influenza pandemic, influenza

Winter mortality

(Jan 29, 2009)

In previous posts we looked at seasonal fluctuations in mortality.  Since the UK is about to experience some particularly cold weather again, we will look at winter mortality in more detail.

The Office for National Statistics in England and Wales produces statistics comparing the mortality of three winter months with three summer ones.  These statistics take the form of excess numbers of deaths in winter, as shown in the graph below:

Excess winter mortality

As can be seen in the above graph, it is the elderly who bear the brunt of excess winter mortality.  There are a number of reasons for this, of which one of the best known is influenza, which is particularly infectious during winter months.  Influenza can kill directly, but it often…

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Tags: season, influenza, winter

Influenza and coronary heart disease

(Aug 31, 2008)

 Every good statistician knows that correlation does not imply causation.  Just because two things appear linked does not mean they are. However, with historical data we often don't have the luxury of carrying out controlled, scientific experiments to see if A really does cause B.

One particularly interesting example is the possible link between influenza and coronary heart-disease (CHD) mortality. The following chart is derived from data from the Massachusetts Department of Public Health Registry of Vital Records and Statistics, and is inspired by a similar chart by Azambuja and Levins (2007):

Dramatic increase in CHD mortality following Spanish Flu pandemic of 1918-1919

While we know that correlation does not imply causation, there does seem to be a rising incidence of CHD along…

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Tags: influenza, CHD, mortality projections, Spanish influenza pandemic, 1919, ICA, stress test, cause of death

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