Why is WHO today saying CFR has increased to 70%?

[Helderflower]

http://www.aljazeera.com/news/afric...-70-percent-victims-20141014132345720164.html

I thought it already was about 70%? Or was I wrong about that...I read it on Flutrackers.

 

[Dani]

Re: Why is WHO today saying CFR has increased to 70%?

http://www.aljazeera.com/news/afric...-70-percent-victims-20141014132345720164.html

I thought it already was about 70%? Or was I wrong about that...I read it on Flutrackers.

For a long time they were saying it was actually 53% with a 47% survival rate, primarily for two reasons- first, they were only counting the ones who were hospitalized not realizing that there were probably at least as many out in the community. Hospitalized patients will do a bit better because of the supportive care, or maybe it's just because they're well enough to get to the hospital. Then they started to count cases in other, often grim ways, such as counting new graves, realizing that folks left in the community will usually die.

The other thing is that early in the epidemic when it is in the exponential growth phase, there are far more new cases on any given day than there were two weeks ago, but it is the people infected two weeks ago who are dying. So one has to go back two weeks (approximately) and see how many total cases there were then. If you just count cases and deaths on any given day when the number of cases are exploding, it will look like more folks are surviving when what it means is that the deaths, sadly, have just not caught up yet. So now they've acquired enough data to do those look-backs and calculate the CFR properly.

 

[sharon sanders]

Re: Why is WHO today saying CFR has increased to 70%?

The official estimates have ranged from approximately 50% to 90% since March depending on the current data and geographic area. I think no one really knows the true percentage but 47%, or 50%, is high enough to classify as a total disaster.

 

[Ray]

Re: Why is WHO today saying CFR has increased to 70%?

Many epidemiologists have been saying 70% for past few months.

 

[AlaskaDenise]

Re: Why is WHO today saying CFR has increased to 70%?

The official estimates have ranged from approximately 50% to 90% since March depending on the current data and geographic area. I think no one really knows the true percentage but 47%, or 50%, is high enough to classify as a total disaster.

I don't expect anything remotely accurate until it's over, but there is no lack of accuracy with the statement...

...is high enough to classify as a total disaster

.

 

[gsgs]

Re: Why is WHO today saying CFR has increased to 70%?

and WHO didn't know that until today ??

...
The other thing is that early in the epidemic when it is in the exponential growth phase, there are far more new cases on any given day than there were two weeks ago, but it is the people infected two weeks ago who are dying. So one has to go back two weeks (approximately) and see how many total cases there were then. If you just count cases and deaths on any given day when the number of cases are exploding, it will look like more folks are surviving when what it means is that the deaths, sadly, have just not caught up yet. So now they've acquired enough data to do those look-backs and calculate the CFR properly.

 

[Dani]

Re: Why is WHO today saying CFR has increased to 70%?

and WHO didn't know that until today ??

I guess not. Those early figures were discussed on Ian Mackay's blog, and he didn't think they were accounting for that lag. Look for his post from Friday, July 4. VDU Down Under (In fact, he called it back then- a CFR of 70-80% Good job, Dr. M.)

To be honest, WHO's numbers aren't that great. It get the impression they get a lot of their data from elsewhere, decide what is best, and publish that. I wouldn't be surprised if they had few in-house statisticians. That's just my feeling though, I certainly don't work there or have any solid info one way or the other.
For instance, there was a grad student who sort of plugged in the numbers back in July and came up with the now-widely-quoted figure of 20,000 cases by the first of Nov. He was a little reluctant about even sharing his numbers, IIRC. I saw that post of his early on, in July, before WHO was even very alarmed about anything. Suddenly, a week or two later up they start quoting this figure, and I didn't think that was coincidence.

They also used those early numbers to urge people to get treated, as it seemed to show a better survival rate than in other outbreaks, so there was some well-meaning propaganda there.

 

[JJackson]

Re: Why is WHO today saying CFR has increased to 70%?

The NEJM report is the only comprehensive analysis of the data to date and 35 of its authors were from the WHO. It set the CFR to 70%. If you read Appendix 1 they go into quite a lot of detail about the state of the data they had to work with. They had access to all the line data from the WHO and the relevant Ministries of Health in each country (this data is not available outside of the WHO collaborating centers). When they calculated the CFR they cleaned all the data to remove obviously incorrect entries (like date of death prior to hospital admission) and then they only selected data for known outcomes either recovered or dead and finally they did not include the very latest data to exclude bias caused by deaths occurring earlier than confirmed releases.

So the WHO do not have a problem with the methodology.
This was a one off for a peer reviewed publication and involved about 50 authors. It is a lot of work to do this and keep it up to date so they must be running a simpler version. In the press conference in which he gave the 'new' CFR figure he did not explain how he reached it but he did give the current totals for confirmed/probable/suspect (8914) and deaths (4447). These give an uncorrected CFR of 50%. The 10 Oct. data was 8376 & 4024 or 48%. On the 3rd it was 46%. As all these numbers come from the WHO road map updates it is reasonable to assume we are comparing like with like. On this basis the uncorrected CFR is rising fairly rapidly and the corrected one must be as well. It is this that has now broken 70%. If these continue to track in parallel it should be possible to estimate the corrected CFR by multiplying crude CFR by 1.4 - at least for a while.
The interesting question is why?
It may be that since the bed capacity became saturated more patients are being cared for at home and they have a lower survival rate. The additional people on the ground and increased lab capacity may be changing data collection and processing with historical data now being input into the system. There are many factors that could be in play. I doubt it is a change on the virus' part it is much more likely to be on the human side of the equation.

 

[Dani]

Re: Why is WHO today saying CFR has increased to 70%?

Thank you for correcting me regarding WHO's capacity to analyze the data. I've seen that article but didn't look at the the authorship, and I'm glad to know they're looking at things closely now. Early in the epidemic, it was hard to get a handle on things and it's great to see some solid numbers coming out.

 

[JJackson]

Re: Why is WHO today saying CFR has increased to 70%?

The maths was solid but I doubt the numbers were. By their own calculation they had an estimated under count factor of 2.5 so most of the cases were never in the data. Also despite it being a great report it only had data up to the 16th of September, which for almost any other scientific paper would be bang up-to-date, but in terms of this outbreak 16th Sept. is just a fond memory.

 

[Laidback Al]

Re: Why is WHO today saying CFR has increased to 70%?

Early on I think WHO was wishing for a CFR of 50%, given the size of the outbreak. By WHO's own data, the average CFR for 25+ Ebola outbreaks is 67% (link).

Perhaps we should be hoping that it is only 70%.

 

[JJackson]

Re: Why is WHO today saying CFR has increased to 70%?

Al
Sadly I think it will be low. The NEJM report only used patient data from treatment centers, MSF etc which implies they were mainly receiving some kind of treatment, even if only fluids. If the estimated under-count is close then more than half are outside 'the system' and are presumably getting less treatment, if any. The uncounted and untreated are not likely to have more favorable outcomes.
Seeing as most of the authors were from WHO they are probably applying similar criteria, in only using the official data as a basis for calculations, and not incorporating any guesses as to what is happening in the unsampled section of the population. If it turns out sweating it out at home is a better option than going to stay with those nice MSF people then the CFR will go down, either that or the other thing will happen.

 

[sharon sanders]

Re: Why is WHO today saying CFR has increased to 70%?

"...early evidence suggests that the Guinea strain of Ebola is related to the Zaire Ebola strain that carries a mortality rate of 90%..."

http://conakry.usembassy.gov/ebolahemorrhagicffver.html


..IAN NORTON:"There will definitely be survivors. We have, at the moment, without care, we know the mortality rate of ebola: it's about 90 per cent in this outbreak. A devastating disease but not universally fatal, even with minimum care"....

http://www.abc.net.au/pm/content/2014/s4086777.htm

 

[JimO]

Re: Why is WHO today saying CFR has increased to 70%?

Using the data available and calculating the CFR by dividing deaths by the sum of deaths + recovered patients has shown a CFR ranging between 75-80%. Unfortunately, there are large numbers of cases in Liberia and Sierra Leone for which no outcome has been reported (and probably never will be). This accounts for about 25% of the cases in Liberia and 40% of the cases in Sierra Leone. So, even when this is all over, I doubt we'll know precisely what the true CFR is.

 

[hawkeye]

Re: Why is WHO today saying CFR has increased to 70%?

The official estimates have ranged from approximately 50% to 90% since March depending on the current data and geographic area. I think no one really knows the true percentage but 47%, or 50%, is high enough to classify as a total disaster.

Wasn't the Spanish Flu assumed to be 2.5%?

 

[sharon sanders]

Re: Why is WHO today saying CFR has increased to 70%?

Wasn't the Spanish Flu assumed to be 2.5%?

Yes.

http://wwwnc.cdc.gov/eid/article/12/1/05-0979_article

 

[MHSC]

Re: Why is WHO today saying CFR has increased to 70%?

Wasn't the Spanish Flu assumed to be 2.5%?

I thought it was 2.5%, but when looking I found this....

http://www.ncbi.nlm.nih.gov/pubmed/20167048

French and American troops who fought in the First World War began to be affected from April 1918 onwards by a benign influenza epidemic, which hardly caused any deaths. The first occidental European country in which the pandemic spread to large sectors of the population, causing serious mortality, was Spain. The associated influenza provoked in Madrid a mortality rate of 1.31 per 1000 inhabitants between May and June (1918). In the following months of June and July, the epidemic spread to Portugal, but did not reach the Pyrenees. In September 1918, the influenza pandemic spread with tremendous virulence, presenting itself simultaneously during the month of October in South Western European countries. In Madrid, the 1918 excess mortality due in large part to the influenza pandemic is estimated at 5.27 per 1000. In Paris, the 1918 mortality rate provoked by the influenza and pathologies of the respiratory system was 6.08 per 1000. In South Western European countries, mortality rates oscillated between 10.6 and 12.1 per 1000 inhabitants. A study of the age distribution of deaths due to influenza between 1916 and 1921 reveals that the Spanish influenza principally affected men and women between 15 and 44 years of age. Deaths associated with the seasonal influenza of 1916, 1917 and 1921 represented 19.7%, 12.5% and 21.0% of all deaths respectively, whereas during the rawest moments of the Spanish influenza, in 1918, the proportion of deaths due to flu for those aged between 15 and 44 years of age reached 68.2% in Paris and 66.3% in Madrid.

 

[BoomerCoop]

Re: Why is WHO today saying CFR has increased to 70%?

and WHO didn't know that until today ??

I think they knew quite a while ago, they had 47% (or was it 53%) on their web site for the longest time. They took it down a couple of weeks ago, as it was obvious the CFR was much higher. They haven't replaced the number with a new statistic.

On another topic, I see where the MOH Site Reports are for Sierra Leone and Liberia, however, don't see any site reports for Guineau. In fact, can't even find the government website. Lots of places link to it, but it doesn't seem to exist.

 

[gsgs]

Re: Why is WHO today saying CFR has increased to 70%?

Sierra Leone reports a CFR of 32.2%
http://health.gov.sl/wp-content/uploads/2014/10/Ebola-Situation-Report_Vol-139.pdf

They had some reclassification of deaths on Oct.4 in Bombali,Tonkalili and Bo
with 293 reported deaths on a single day, most of which apparently occurred earlier.

But even with that correction their death-counts are way off.
See http://magictour.free.fr/whoe41b.GIF how reported deaths continuously went
down in weeks 36,37,38,39 in Sierra Leone, while cases increased.

deaths/cases:
Sierra Leone:1198/3296=.363
Liberia:2458/4249=.578

Liberia reports a CFR of 66.1%, they take confirmed and probable cases here.

 

[Lizw]

Re: Why is WHO today saying CFR has increased to 70%?

This is total speculation on my part, but after reading the thread about the mutations in serial passage caused by unsterile needles, one has to wonder whether the apparent sudden virulence of the 1918 flu might have been related to unsterile practices. Just a thought...

ench and American troops who fought in the First World War began to be affected from April 1918 onwards by a benign influenza epidemic, which hardly caused any deaths. The first occidental European country in which the pandemic spread to large sectors of the population, causing serious mortality, was Spain.