https://www.worldometers.info/coronavir ... eath-rate/
What we were discussing in the other thread:
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The case fatality rate (CFR) represents the proportion of cases who eventually die from a disease.
Once an epidemic has ended, it is calculated with the formula: deaths / cases.
But while an epidemic is still ongoing, as it is the case with the current novel coronavirus outbreak, this formula is, at the very least, "naïve" and can be "misleading if, at the time of analysis, the outcome is unknown for a non negligible proportion of patients." [8]
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In other words, current deaths belong to a total case figure of the past, not to the current case figure in which the outcome (recovery or death) of a proportion (the most recent cases) hasn't yet been determined.
The correct formula, therefore, would appear to be:
CFR = deaths at day.x / cases at day.x-{T}
(where T = average time period from case confirmation to death)
This would constitute a fair attempt to use values for cases and deaths belonging to the same group of patients.
Quote:
An alternative method, which has the advantage of not having to estimate a variable, and that is mentioned in the American Journal of Epidemiology study cited previously as a simple method that nevertheless could work reasonably well if the hazards of death and recovery at any time t measured from admission to the hospital, conditional on an event occurring at time t, are proportional, would be to use the formula:
CFR = deaths / (deaths + recovered)
which, with the latest data available, would be equal to:
159,747 / (159,747 + 595,381) = 21% CFR (worldwide)
If we now exclude cases in mainland China, using current data on deaths and recovered cases, we get:
155,115 / (155,115 + 518,352) = 23.0% CFR (outside of mainland China)
This is the most comprehensive explanation I found on the death rate.
As you can see, the total deaths / total number formula is plain wrong because you're assuming the whole denominator will survive + due to the reasons explained in the link; so the death rate among the confirmed cases is much much worse than the 2-4% that keeps repeated in the media.
This part is interesting too:
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Finally, we shall remember that while the 2003 SARS epidemic was still ongoing, the World Health Organization (WHO) reported a fatality rate of 4% (or as low as 3%), whereas the final case fatality rate ended up being 9.6%.
We will get the right rate only after the end of the epidemic , and after finding a mechanism to determine how many unconfirmed cases (as % of a population) we had - probably by testing their antibodies. What we have now can be a case of selection bias.
15 Apr 2020, 11:33 pm
