It appears the @EpiEllie was correct in that lead-time bias is probably a large part of the reason that deaths are lagging behind hospitalizations this time around
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It’s not a bias.
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Replying to @mikejohansenmd @EpiEllie
Health Nerd Retweeted Dr Ellie Murray, ScD
From an epidemiological perspectivehttps://twitter.com/EpiEllie/status/1280305393516904448?s=20 …
Health Nerd added,
Dr Ellie Murray, ScDVerified account @EpiEllieTHINK LIKE AN EPIDEMIOLOGIST: why are COVID deaths *still* not going up 3 weeks after case counts started increasing? There are many possible explanations, but one I haven’t seen mentioned is the impact of widespread testing on *early detection*. A#tweetorial on LEAD TIME BIAS.Show this thread1 reply 0 retweets 3 likes -
Aware, lead time is not a bias. It’s lead time.
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I agree there is poor understanding, but it’s not a bias.
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Replying to @mikejohansenmd @GidMK
I think the bias is when you assume that the outcome is less frequent because you don’t realize that one group includes lead time—which is what people were doing with COVID a few weeks ago, claiming it was getting less fatal instead of realizing that the lead time had changed.
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I don’t see this as the same lead time issue that we see in cancer screening. It’s just the expected ~3 week delay until we see the expected mortality. It’s not that we are catching the disease earlier.
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Replying to @mikejohansenmd @EpiEllie
I disagree. In April, particularly in the US, you had to be really quite sick to get tested in many places. Now testing is common for presymptomatic people, who may then go on to develop symptoms weeks later
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Obv agree w/your statement. That would mean we are comparing CFR's, would be an error to compare given differences in testing. If you did, lead time obv becomes an issue. The death rate is more or less a formula that is driven mainly by age. I don't find this to be a bias.
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Yes, agreed. I think we may be talking about different things - there was an argument that the recent increase in cases was somehow less fatal than the previous rise because there were fewer deaths, but this seems to be explained by the lead times
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We agree! Twitter ftw. I object to the use of the term bias. I think the same thing w/immortal time. It's immortal time. People's analyses are biased. Lead time is the concept, the bias is the analysis. This was actually helpful in better understanding this.
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