Coronavirus: why mortality and death rates differ


But what if they had an underlying condition, like asthma, which was exacerbated by Covid-19? Or what if the patient dies of something that seems less related to Covid-19, which is a respiratory disease – like, for example, a brain aneurysm? What condition should be considered the cause of death?

Even within a country, official statistics can vary depending on what you count. In the UK, for example, the Department of Health and Welfare publishes daily updates on the number of people who tested positive for Covid-19 who died on that day. This includes any patient who has tested positive for Covid-19 but who may have died from another illness (for example, terminal cancer). But the UK Bureau of National Statistics counts all deaths as Covid-19, where Covid-19 was mentioned on the death certificate, whether they were tested or simply if it was a suspected case of Covid- 19. Adding to the complexity of trying to understand mortality rates is that the two are not synchronized, since the ONS counting mode can only occur after the issuance of a death certificate, so takes more time.

“The problem is not really about good or bad, but the fact that each data source has its own strengths and weaknesses,” writes Sarah Caul, head of mortality analysis at the NSO, in an article by blog on the different ways of counting deaths.

It is not necessarily a source of divergence Between most countries, however, like many count deaths in the same way. Italy counts any death of a patient who has Covid-19 as a death caused by Covid-19; Germany and Hong Kong too.

Physicians in the United States have more discretion: they are asked to record if the patient died “as a result of this disease” when the Covid-19 deaths were reported to the Centers for Disease Control and Prevention. It might be easy to see how a doctor might believe that a Covid-19 patient who died, for example, from a heart attack or brain aneurysm is not dead result Covid-19, and would therefore not report accordingly.

But what is important, although it can make a difference when the data is analyzed in months or years, it does not translate into a difference in the death statistics yet. Currently in the United States, any death of a Covid-19 patient, regardless of the doctor’s direct cause, is counted as a Covid-19 death.

“I expect the final death certificate to contain Covid as well as pre-existing conditions, if any,” said Cécile Viboud, epidemiologist at the Fogarty International Center at the National Institutes of Health. “But at this point, any positive Covid case that dies will be counted toward the death toll in the United States. “

So what counts as a Covid-19 death will affect our overall understanding of the lethality of the disease in the long term, but it probably doesn’t play a huge role between countries.

Complex causes

The picture is even more blurred when the patients were not tested for Covid-19, but were in a suspicious case. Since many deaths from Covid-19 occur in people with underlying health conditions, doctors should always call the cause of death.


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