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Science

The Misnomer of Case Fatality Rate

smjWritten by Rod Mishler and Sean Maurice Jefferson

Sunday, April 26, 2009: U.S. Declares Public Health Emergency Over Swine Flu

Thursday, June 11, 2009: The WHO Declares the Swine Flu a Level 6 Pandemic

From the above headlines, one would think the Bubonic Plague or Black Death had returned from the ether to rain impending doom upon us all.

It’s now fairly certain that humans did in fact give this brand of virus to the swine. Modern science has re-analyzed the 1918 version and now states that the contagion did in fact migrate from birds, to humans, to swine, only to return most recently after mutation to humans once more. It’s also now fairly apparent that Mexico, not Hollywood, was the source of the Keystone Kops of legend. Their slow footedness and lack of credibility within their own citizenry created a situation that had the world’s public health groups wearing their political thinking caps, instead of those of the Hippocratic variety.

Mexican Keystone Cops you say? A little harsh perhaps, maybe, maybe not, but they had company and plenty of it. At one point some time ago, a medical issues blogger noted that the CDC had 91 H1N1 confirmed cases on one web page, but declared 64 on a separate web page. If the CDC were a private organization, lawyers would be filing papers, oh file them they would.

It’s also now blatantly clear that the H1N1 virus does not have a significantly different CFR than the common flu. How do we know this? Because we’ve now had more than enough time to study it adequately. 328,426 confirmed worldwide cases, 3,430 deaths which thus far equates to a CFR of around 1%. 1918 Swine Flu CFR estimates; 2.5 to 5%.

Pneumonia and Influenza Mortality for 122 U.S. Cities

View Full Screen Version of Chart

Seasonal flu viruses spread around the globe and cause 250,000 to 500,000 deaths each year worldwide — including some 20,000-36,000 annual deaths in the U.S. But seasonal flu isn’t considered a pandemic, even though the viruses that cause them change a little from season to season. (http://www.medicinenet.com/script/main/art.asp?articlekey=101107)

What’s CFR you say? Case Fatality Rate or Ratio. It’s like it sounds. What’s the death rate if you’re infected. Rabies has a CFR of ~1.0. You get infected, you get symptoms, you die. Whereas the common flu is purportedly <.01 or 1%. So, you can consider that CFR has 3 ranges, in order of magnitude, that could be classified as: .001, .01 and .1, or 0.1%, 1% and 10%. So, rabies, ~100% CFR. Common Flu 1% CFR. A most significant difference indeed.

Bad science:

The 1918 Spanish Flu numbers, e.g., http://en.wikipedia.org/wiki/Spanish_flu (note that this is a page with 66 references)

70 to 100 million died;
0.025 to 0.05 CFR;
20 to 50% infection rate.

But, those numbers just don’t work.

Sample A:
100,000,000 dead ÷ .05 CFR = 2 billion people infected
2,000,000,000 ÷ .5 or 50% infection rate = which would equate to a world population of 4 billion

Sample B:
100,000,000 dead ÷ .05 CFR = 2 billion people infected
2,000,000,000 ÷ .2 or 20% infection rate = which would equate to a world population of 10 billion

Sample C:
100,000,000 dead ÷ .025 CFR = 4 billion people infected
4,000,000,000 ÷ .5 or 50% infection rate = which would equate to a world population of 8 billion

Sample D:
100,000,000 dead ÷ .025 CFR = 4 billion people infected
4,000,000,000 ÷ .2 or 20% infection rate = which would equate to a world population of 20 billion

Sample E:
70,000,000 dead ÷ .05 CFR = 1.4 billion people infected
1,400,000,000 ÷ .5 or 50% infection rate = which would equate to a world population of 2.8 billion

Sample F:
70,000,000 dead ÷ .05 CFR = 1.4 billion people infected
1,400,000,000 ÷ .2 or 20% infection rate = which would equate to a world population of 7 billion

Sample G:
70,000,000 dead ÷ .025 CFR = 2.8 billion people infected
2,800,000,000 ÷ .5 or 50% infection rate = which would equate to a world population of 5.6 billion

Sample H:
70,000,000 dead ÷ .025 CFR = 2.8 billion people infected
2,800,000,000 ÷ .2 or 20% infection rate = which would equate to a world population of 14 billion

Thus, given the quoted sampling numbers, the worlds population was between 2.8 and 20 billion people. Problem is, the world’s population was believed to be 1.8 billion in 1918.

OK, so let’s try a 30% infection rate with a CFR of 0.1 or 10% (the high end of the CFR scale). These numbers equate to 54 million (H1N1) deaths in 1918. This seems more reasonable, but nobody knows for sure. The literature of that time, even of a strictly medical nature, is nothing more that very bad science. Even the U.S., which had probably the best data available, only had a 30% infection rate (the same as the common flu) and a CFR of ~0.018, or around 2%! But a 0.018 CFR is quite different than the 0.1 or 10% that we said a moment ago was maybe a more reasonable number from the 20 to 50% infection rate quoted in the sampling.

The point is: Yes, there were lots of deaths. How many? Nobody knows with much scientific certainty, but to get deaths in excess of 25 million, you either need a big CFR or a very big infection rate. Since it appears that nobody wants to quote an infection rate greater that 50%, you either need a very big CFR, or the deaths were nowhere close to 100 million in 1918.

I guess that the U.S.’s CFR of .02 was not a big deal in those days. Besides, WWI was in progress… far, far more people were dying due to war, and don’t think that a world war didn’t have an effect on infection rate, pandemics love world wars, especially trench warfare. Conversely, quarantine was common in 1918, allowing for the containment of disease once identified. To that note for example, Trinidad and Tobago had the highest reported cases of the AIDS virus in the Caribbean in 1994. During 1983-94 there were 1657 cases of AIDS and 1079 deaths (a case fatality ratio of 65.1%). Quarantine? Not politically possible. Why? Because most notably it may take 30 years or longer to die from that particular virus if infected. Also, note that the AIDS CFR is being hidden by a related cause of death such as tuberculosis. My sister (Rod’s), a nursing instructor, commented to me about 10 years ago that AIDS is a future major pandemic waiting to happen due to politics. It could take 10 or more years to happen, but it will happen. The question is will we be prepared? Note that today the WHO estimates that AIDS has killed 25 million people worldwide.

So let’s switch focus for a moment for the sake of perspective and look at the infamous 2003 SARS outbreak. The official WHO data has it at a CFR of .096. That’s a pretty big number. But it’s widely known that Canada had a CFR of .17 or 17%, while the US had a CFR of 0.0, no, that’s not a misprint, the difference was in the treatment, not the virulence. The Canadian patients died at the hands of their treatment, not their contagion! In fact, many attribute all SARS deaths to the treatment regimen; the Mexicans weren’t the first “Pandemic Keystone Kops”, go ahead at this point and add our neighbors to the north, Canada to the list. It’s the reason why there were zero deaths in U.S. in addition to all of Europe. You see, bad science and poor politics can affect CFR as much as anything, a thought well worth noting. The main point of this paper is, don’t get too caught up in the CFR numbers, they are all over the place depending on who’s numbers you read. There are more factors involved in the fatality ratio than virulence, like economics, demographics, geopolitics, treatment regimen, and frankly bad science.

OK, so why the current “Kernel Panic” if you will? Well, simply put, because this 2009 version is of the same virus family as the 1918 version, and that killed tens of millions. That fact tends to get a person’s attention fairly quickly as they wiki-research in the 21st century.

To the CDC’s credit, they do make a specific CFR distinction in their Pandemic Severity Index, whereas the WHO (World Heath Organization) does not, hence the reason we’re a little hard on the WHO. Conversely, the CDC has 5 categories between <.001 and >.02 which are explained as being equivalent to the Saffir-Simpson Hurricane Scale. Bad, bad, oh so very bad. Are they trying to say that pandemic fatalities make a CFR of <.001 somehow equivalent to a Category 1 hurricane? Has anyone bothered to ask how the common flu is in any way like a Category 1 hurricane? Again to get too caught up on numbers is dangerous and can lead to panic-think. Slapping a name on a virus doesn’t make it any more virulent. The media is hungry for the next big viral terror, because that’s what sells papers, SARS, Avian, Swine, Legionaries Disease, Mad Cow, all serious outbreaks and worthy of our attention without a doubt, but when you look closely at the 1918 Swine Flu outbreak versus the current outbreak ,you’re not comparing a 1918 Category 5 Hurricane to a 2009 Cat 5, now are you?

Oh, and by-the-by, Category 5 of the WHO’s 6 category pandemic scale would equate to: person-to-person transmission in two countries in the same part of the world. Say, how’s that different from the common flu transmitted via people on vacation traveling outside their own home country, that’s equivalent to a Cat 5, WHO? Let a Cat 5 Hurricane pass over your headquarters sometime and you’ll get a real sense of scale and how inaccurate yours truly seems to be. When we talk about bad science in this article we’re referring to data that is grossly misplaced and categorized and the apprehension that it can instill in the media and general public who are hungry for sensationalized information. Again, reference the SARS case, did it have a 17% CFR or 0% CFR, well, that depends now doesn’t it on where you lived and how you were treated, same thing with AIDS, the infection rates and CFR in rural Africa are far different than those Beverly Hills, CA for those with the same damn virus.

So, the bottom line is that the general world health organization community continues in the 21st century down a cobble stone road of bad science and suspect reporting practices and at times takes major hits to its credibility in the public eye. What else is new? It would seem that they have historically taken the same path and attitude as the weather forecasting community…”Without us, what have you got?” Nothing, I suppose; but a need to carry an umbrella every time one sees a herd of dark clouds in the overhead sky…just to be on the safe side. We’re not downplaying the health risks associated with these viruses, especially H1N1, we’re just saying, take the published numbers for what they are, more like weather estimates in a 7 day forecast, use good judgment when reviewing information gleaned from the media, they sensationalize because that’s what sells. H1N1 isn’t a Category 5 hurricane, if it was, you wouldn’t be around to even read this article, you’d be dead or in a bunker somewhere riding this storm out, an exaggeration, but still, you get the point of the analogy, I hope. Now please excuse me while I go down a mega dose of Vitamin C, I talk a good game like Franklin D. Roosevelt (“The only thing we have to fear…”), but I don’t want the flu this season anymore than the next guy, even a mild version is a major pain.

My co-writer for this article, Rod Mishler is a Senior Data Analyst and Data Client Operations Manager for a major data information management company in the U.S. and has a master’s degree from Carnegie Mellon University.

See other articles by this author below:

The Misnomer of Case Fatality Rate

Jade

The Psychology of Post Nuclear Generations

The Immortality of The Human Cell

NanoBioElectromagnetics

The Dawn of Socialized Banking in America

7 Day Eclipse – An Anthology of Poetry

The Theistic Multiverse Part I (The Philosophy)

The Theistic Multiverse Part II (The Math)

About sjeffers1

Sean Maurice Jefferson has written 9 post in this blog.

  • admin

    I’m Canadian and I think it is worth pointing out that ALL SARS related deaths in Canada were in ONE city, Toronto. I think that might help prevent people from forming an obfuscated view of Canada’s health care system. Especially when this article discusses, at length, misinterpretation of data and the misleading conclusions that can be made from it. Obviously… the situation was compromised for the people in Toronto, because, taking a closer look, Canada had more cases of SARS than the States and in reality prevented more deaths from SARS than the States. I have accepted a zero tolerance attitude towards the flak so often emanating from our neighbors to the south. How can anyone be expected to believe that the health care system of America is something we Canadian’s should be jealous of? The States remains the only developed country without universal health care and if we look at where the good ol’ U.S. of A stands in terms of health care when compared to Canada we would see the 37th spot is occupied by the US and the 30th by Canada. If we were to investigate further and examine life expectancy we would find Canada sitting comfortably in 8th place, and America (maybe not so comfortably) in 50th. I can say I agree with most of the points of this article though, so maybe we should all just get used to the American attitude.

    Posted by Chad Bergman, on 09/21/2009 at 19:50

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