Dr No recently came across a number of reports in the mainstream media suggesting that the median age of those dying from covid–19 was a little higher than the median age for all deaths: 82.4 for covid deaths, against 81.5 for all deaths. Putting aside the inevitable journomonologophobia that gave rise to a swirling word salad of averages, means and medians in the reports, the finding gives rise to the clinically intriguing possibility that the best way for elderly people to live longer in 2020 was not to bother with all that shielding nonsense, but instead get out there and catch the damn thing. On more sober reflection, Dr No wonders if one or more biases may be at work, but let’s for a moment consider that the reported findings are true. If they are, it gives yet more weight to the notion that the burden of covid–19 falls with greatest weight on the very old. If the median (middle value when all are ranged from top to bottom) age for covid deaths is 82.4, then half of all covid deaths occur in those aged 82.4 and over.
All of the reports, including those in the Times (paywall), the Daily Mail and the Sun, give their source as a study done by the Centre for Evidence Based Medicine in Oxford. This seems plausible, given the CEBM’s penchant for pricking pandemic balloons, a plausibility reinforced by the detailed further and better particulars in the reports on the numbers from the study. Hot on the trail, Dr No set off into Googleland with all his favourite search tricks to hand — and drew a complete blank. Unless a reader manages to find the original study, it appears it has never been published. It is possible, Dr No supposes, that the CEBM put out a press release and nothing else, but that would be highly unusual. So, once again, it looks as though we have yet another bummer number. Given that we have no way of verifying the data and methods used, we have no way of knowing whether the figures reported, 82.4 and 81.5 are fact or fantasy.
So what are the real median ages for covid deaths and all deaths? After more time in Googleland, Dr No came across this response from ONS to a request for the covid element of the question. Based on deaths up to 2nd October, the median age for all covid deaths in England and Wales was 83 (81 for males, 85 for females). The means were also reported, at 80.4, 78.7 and 82.5 respectively, but not the mode (commonest age at death). It seems that, even though the source appears ephemeral, the 82.4 figure is near enough, in the horseshoes and hand grenades sort of way, but we’ll use the ONS figure as we have a direct source, and say 83 is the median age for covid deaths.
Median age at death is only one measure of longevity, and is not routinely reported by ONS. Instead, it tends to prefer life expectancy, a vaguely mind bending sort of mean statistic based on a little light touch numerology. What exactly do we mean if we say, for instance, that life expectancy today is 80 years? Another measure is the mode, or commonest value. All of these are stabs at summarising in a single figure where the typical, in the middle value lies. Means (averages) work well for Normally distributed (the symmetrical bell shaped curve) variables, but fail, often spectacularly, with skewed (asymmetrical) distributions, including age at death, which is heavily skewed to the right (most people die when they are old). For these heavily skewed variables, the median (middle value when all are ranged top to bottom) gives a better sense of the typical, in the middle (which it literally is) value.
ONS do publish annual tables of deaths by single year of age for England and Wales, and these are more than enough to provide a very good estimate of the median age at death. Because these tables are aggregates of all deaths, all we need to do is find the year that includes the middle (total deaths/2) death. What we find from the latest data (for 2018) is that for all persons, the median age at death is 80-81 (nearer 81, lets say 81.7). As the tables also report deaths by sex, we can do the same for males and females, and note that for males the median at death is 78-79 (somewhere in the middle, lets say 78.5) and for females it is 83-84 (somewhere in the middle, lets say 83.5).
It turns out that, even if the CEBM research is ephemeral, the findings are not far off the verifiable figures, which are if anything even more striking. The alleged CEBM median ages are 82.4 (covid deaths) and 81.5 (all deaths), whereas Dr No’s verifiable figures based on ONS data 83 (covid deaths) and 81.7 (all deaths). Both medians are marginally higher, but more striking is the difference between the covid and all cause medians, which has risen from 0.9 years to 1.3 years. Folks with covid tend to live over a year longer than those without. Perhaps covid really is good for you, after all!
Of course it is not. There is almost certainly a selection bias at work here. What we might expect, without the bias, is that covid pushes frail birds off their perches a little early, so they die a little early. But this does not appear to happen. One possible, indeed likely, explanation is that covid selects (the bias) the really really frail, and to be really really frail you have — by and large, we are talking at population level here — to be really really old. The median age at death for covid is higher because, by and large, you need to be very old, and very frail, for covid to stand a reasonable chance of pushing you off your perch.
The two by and large qualifications in the last paragraph are there because of course there are exceptions, just as there is long covid, but by and large the brutal fact is that fatal covid is overwhelming a disease of the very old. This is borne out by other observations. The ONS weekly data consistently show — this is the easy to remember one — that 75% of covid deaths occur in those aged 75 and over, and that getting on for half (42%) of the deaths occur in those aged 85 and over, a figure fully consistent with a median age at death of 83 years old. The same data, by the way, show that for children up to and including the age of fourteen — so very much the schoolchildren so often in the news these days as biological covid bombs — the risk of fatal covid is almost vanishingly small, with only seven deaths, very likely in those with pre-existing conditions, occurring in this age group.
Though grim for most of the very old, though not all, because some will feel themselves ready to take the final journey, these findings are in another way a cause for optimism. To the extent that fatal covid is very much a disease of the old, then it is also not a disease of the young and middle aged. And buried within all this, though hard to prove at this stage, as we lack complete data, there is another possible cause for optimism, and indeed explanation of why the current seasonal increase in deaths is not as bad as the spring peak — the latest seven day moving average peak, in late November, topped at just under 500 deaths, compared to just under 1,000 in the spring. If fatal covid overwhelmingly attacks the very old and frail, then on its first arrival it will operate very much in the same way that a first, or prevalence, screening round works: there will be many cases/fatalities, because of the larger pool, accumulated over time, of pre-clinical/susceptible people. Subsequent screening rounds, or infection waves, affect fewer people, because the pool is now only made up of new (incident) pre-clinical/susceptible people that have appeared since the last screening round or infection wave. There is simply, to use the incendiary phrase, less dry tinder in the grate, and any subsequent fires will be smaller.
The hard facts, and these are hard facts, not scenarios, projections, estimations, models, lottery numbers, astrological predictions or numerological fancies, of the age distribution and median age for covid deaths are brutal facts, particularly for the very old and their family and friends. But they also provide a much needed sense of perspective, of what covid really is, and, just as importantly, what it is not. We need that perspective now, more than ever, if we are to move back to the old normal, and a practical, sensible and above all else proportionate response to this novel seasonal flu like illness.