2/n The paper is here, if you want to have a gander:https://www.medrxiv.org/content/10.1101/2020.05.13.20101253v1.article-metrics …
-
-
Show this thread
-
3/n What did the study consist of? Well, the aim is to estimate the infection-fatality rate (IFR) of
#COVID19 using seroprevalence (antibody test) studies The methodology here is not ideal at first glancepic.twitter.com/9d9V7qmTys
Show this thread -
4/n What's the issue? Well, if you want to estimate a number like this from published data you want your search and appraisal methods to be SYSTEMATIC Hence, systematic review
Show this thread -
5/n Instead, what we appear to have here is an opaque search methodology, little information on how inclusion/exclusion criteria were applied (and no real justification for those criteria)pic.twitter.com/35EYmKMBFE
Show this thread -
6/n For example, seroprevalence studies including healthcare workers were excluded, because the samples are biased, but studies including blood donors were not, even though these are arguably even more biased That's a strange inconsistency
Show this thread -
7/n Studies only described in the media were excluded, but this appears to have included government reports as well Again, there's no justification for this and it is REALLY WEIRD to exclude government reports (they're doing most of the testing!)
Show this thread -
8/n Moving on, the study then calculated an inferred IFR, if the authors hadn't already done so. The calculation is crude, but not entirely wrong However, there's an issue - the estimates were then 'adjusted'
Show this thread -
9/n Spefically, the IFR estimates were cut by 10-20% depending on whether they included different antibody tests or not I had a look at the reference here, and it definitely doesn't support such a blanket judgementpic.twitter.com/AYzDRR5suk
Show this thread -
10/n Ok, so, on to the results This table is basically the crux of the review. 12 included studies, with "corrected" IFR ranging from 0.02-0.4% MUCH lower than most published estimatespic.twitter.com/hDyd9YQgOL
Show this thread -
11/n A colleague and I did a systematic review and meta-analysis of published estimates of IFR and came to an aggregated estimate of 0.74% (0.51-0.97%) so this is a bit of a surprise to me https://www.medrxiv.org/content/10.1101/2020.05.03.20089854v2.article-metrics … What's happening here?
Show this thread -
12/n Looking at this table, there are some things that immediately spring out Firstly, three of these studies are of blood donorspic.twitter.com/5wyn4wPbXD
Show this thread -
13/n It is pretty easy to see why these studies aren't actually estimates of IFR - blood donors are by definition healthy, young etc, and so any IFR calculated from these populations is going to be MUCH lower than the true figurepic.twitter.com/EaJZlygIRc
Show this thread -
14/n But if we look at the other included studies, this problem is repeated. The French and Japanese studies both used highly-selected patient populations, both of which likely would lead to a biased (low) estimate of IFRpic.twitter.com/imYkR1aEyN
Show this thread -
15/n (The same concern has been raised about the Santa Clara study at the bottom, but for now let's ignore that and move on)
Show this thread -
16/n Remember when I said that the calculation of individual IFRs was reasonable? Well, there's a problem here. When Ioaniddis calculated IFRs, he did a decent job. However, some of the INCLUDED STUDIES didn't
Show this thread -
17/n For example, the Iran, Kobe, and Brazilian studies made no attempt to account for right-censoring That's an issue, as I describe here https://twitter.com/GidMK/status/1262563856456445952?s=20 …pic.twitter.com/dSoRieF29E
Show this thread -
18/n In addition, the Iranian study uses the official figure for deaths, and as has been pointed out this number may be a significant underestimatepic.twitter.com/AQBSIirjRF
Show this thread -
19/n So, a problem The red-outlined studies are clearly not estimates of population IFR - they look at specific, selected individuals and can't be extrapolated The orange-outlined studies are likely underestimates due to methodologypic.twitter.com/b4bZBslEpN
Show this thread -
20/n If we exclude these potentially misleading numbers, the lowest IFR estimate immediately jumps from 0.04% to 0.18% Coincidentally, that 0.18% is Ioannidis' own researchpic.twitter.com/PlaOSJ1AbB
Show this thread -
21/n To me, a low estimate of 0.18% makes MUCH more sense than a minimum of 0.02% for IFR Why? Well, take New York. ~16,000 deaths in a city of 8.4 million means that if every single person has been infected the IFR would be 0.19%pic.twitter.com/pmA8oM4nSm
Show this thread -
22/n Now, everyone calls NYC an outlier, and perhaps it is, but if you repeat this calculation for other places in the States, the same chilling thing happens: Massachusetts: 0.9% New Jersey: 0.12% Connecticut: 0.1%
Show this thread -
23/n The same is true of other places overseas - Lombardy has a total death toll of 0.16%, Madrid is around the same, even London is above 0.1% dead due to COVID-19 It seems INCREDIBLY unlikely, at this point, for the IFR to be below 0.1%
Show this thread -
24/n Now, this is noted in the preprint, but basically dismissed as the deaths of old and poor people That's...not a great perspective imopic.twitter.com/2Zd2se4CyT
Show this thread -
25/n In particular, Ioannidis argues that places with lots of elderly and disadvantaged individuals are "very uncommon in the global landscape" This is trivially incorrect. Most of the world is far worse off than people in NEW YORK CITYpic.twitter.com/HzmUcBdq0V
Show this thread -
26/n There's also some discussion of the obviously underestimated studies, which begs the question why they were included in the first place? They are clearly not realistic numberspic.twitter.com/PFpfWbNTZk
Show this thread -
27/n ...and then a paragraph about Iran that contradicts the earlier points raised about why NYC has seen so many deathspic.twitter.com/u70mD8SEWH
Show this thread -
28/n Some discussion about press release science (we are agreed that it isn't good) but no mention of government reports This is a HUGE gap to the study
Show this thread -
29/n For example, why wasn't this Spanish seroprevalence study included? It is the biggest in the world, and estimates IFR to be ~1-1.3% - triple the highest estimate in this review!pic.twitter.com/VUxKFVNO2O
Show this thread -
30/n On the other hand, why were clearly biased estimates included? Why was 500 arbitrarily the minimum size considered for included research (if you choose 1,000, the IFRs are suddenly much higher)
Show this thread -
31/n Which brings us to this conclusion, which is, frankly, a bit astonishing Is it a fact? That's certainly not shown in this review, and most evidence seems to contradict this statementpic.twitter.com/V9LKRjHKHv
Show this thread - Show replies
New conversation -
Loading seems to be taking a while.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.