Wednesday, 8 April 2020

Covid-19: death stats - announced deaths versus reality.

The Department of Health release daily statistics on the Covid-19 crisis, including the number of deaths and the number of tests. These headline figures are then splashed over the media ("UK records highest daily death toll from coronavirus at 854").

Reporting-wise, the announced statistics on tests have recently improved, with both the number of tests performed and the number of people tested released. The number of people tested is always lower than the number of tests performed, for many reasons: the accuracy of the test is low, a negative result might need confirming, someone might have developed new symptoms after a test, test failures, etc, etc.

However, the deaths data released is oddly lumpy. For instance, over the last few weeks, there have generally been fewer reported deaths on Sunday and Monday, and then new highs on Tuesdays. Why is this? Is there a medical reason?

Probably not. Instead, it is much more likely to be administrative, with fewer staff on-hand to report deaths on weekends, and the unreported deaths being reported in bulk on Monday. These are then shown in Tuesday's figures, producing a slump in deaths followed by a spike.

The deaths announced are only those that occur in hospital; figures for deaths from Covid-19 in the community are harder to compile in the absence of copious numbers of tests. However, even the reduced number relating to hospital deaths can be massively useful for planning purposes, as long as it is consistently compiled.

A major issue is that deaths are not immediately reported. For instance, doctors and nurses have other things to do, autopsies may be required, relatives may have to be informed before the figures are compiled, and there might be a general lag in the system. This essentially makes the charts of deaths shown on the media useless for planning, as deaths announced today may have occurred up to a week ago.

Fortunately, the Department of Health have produced oodles of lovely data that highlight this, split down to trust level:

https://www.england.nhs.uk/statistics/statistical-work-areas/covid-19-daily-deaths/

The figures look very different to those published in the media, and are a lot less noisy. For instance, the 'announced' number of deaths on the first of April was 569; the 'real' number of patients who died on that day was 495. Those 74 patients still died, but they died on previous days.

This is the data we should be making informed decisions from, not the charts from 'announced' deaths shown so frequently on Twitter, Facebook and the media.

It's a shame the media can't be bothered to report this correctly and actually inform the public. Heck, an educational program on the statistics would be brilliant (a TV version of 'more or less').

The media are having a very poor war.

(Apologies; I'm sounding a little tin-foil hatty here).

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