Friday, October 09, 2009

Dead Reckoning



# 3817




Dead reckoning (DR) is the process of estimating one's current position based upon a previously determined position, or fix, and advancing that position based upon known or estimated speeds over elapsed time, and course. - Wikipedia


One of the ploys of the pandemic deniers is to use the `official’ tally of deaths, both here in the US and around the world, to `prove’ the H1N1 virus is not a genuine threat.  


After all, as of October 2nd, even the WHO (World Health Organization) can only come up with a little more than 4,100 deaths worldwide since this outbreak began in April.


And they should know, shouldn’t they?


Unfortunately, they don’t.  No one does. 


Why?  Because we aren’t trying to count the number of deaths anymore, and even when we were -  back in the summer - we weren’t doing a particularly good job of it.


This is a problem I’ve discussed many times over the past few months, including in:


Numbers Don’t Tell The Whole Story
A Decided Lack Of Data
Measuring The Severity Of A Pandemic
Arizona & Illinois Report Swine Flu Related Deaths


Mike Stobbe, of the AP, has a good article on the problem this morning, which explains that the US, along with many other countries around the world, have quit trying to count pandemic cases.


First the article, then some discussion.


US, other nations stop counting pandemic flu cases

(October 9th, 2009 @ 2:11am)

AP Medical Writer

ATLANTA (AP) - U.S. health officials have lost track of how many illnesses and deaths have been caused by the first global flu epidemic in 40 years.


And they did it on purpose.


Government doctors stopped counting swine flu cases in July, when they estimated more than 1 million were infected in this country. The number of deaths has been sitting at more than 600 since early September.


(Continue . . . )


As I wrote back in May, we really have no idea how many people die of influenza during a normal season.  The CDC’s estimate of 36,000 deaths each year is just that – an estimate – an average based on mathematical modeling 


No one counts individual flu deaths.  


Every day in the US, somewhere over 6,000 people die from a variety of causes.   Despite the CSI-induced fantasy that every death gets investigated down to the last hair or fiber, the truth is, unless there is reason to suspect foul play or unusual circumstance, most deaths are handled as routine events.


If someone dies at home, and they are under the routine care of a physician (the definition varies by state), it is considered `an attended death’. In that case, the patient’s doctor may elect to sign the death certificate without ever examining the deceased, and no autopsy is performed.


While rarely stated, there is actually a bit of a built-in disincentive for conducting a post mortem exam. An autopsy could conceivably uncover a missed diagnosis, and that could prove problematic for the doctor.


In funeral home parlance, this is sometimes referred to as `burying one’s mistakes’.


Even in cases where an autopsy is performed, testing for the influenza virus generally isn’t a part of the procedure.  If there are gross signs of lung inflammation, then pneumonia may be cited as a cause of death.


Unless someone dies in the hospital while being treated for influenza or pneumonia, it is highly unlikely that influenza will be listed as an official cause of death. 


One exception to this rule is when the deceased is exceptionally young.   Generally speaking, the younger the victim, the more scrutiny we give the cause of death. 


Here in the US, pediatric deaths (under age 18) from influenza and pneumonia are a reportable disease.  During an average year somewhere between 50 and 100 pediatric deaths are attributed to influenza. 


In 2005-06 there were only 46 pediatric deaths, in 2006-07 there were 78, and in 2007-08 there were 88


As of last week, there were 128 for this year.   Later today we will get a new tally, and based on yesterday’s MMWR report, that number will jump appreciably. 


What is particularly worrying is that over the summer, during a time when we might normally see no more than 1 or 2 pediatric flu deaths, we’ve seen at least 60 due to swine flu.

This grim metric may be our best, most accurate indicator of the impact of the pandemic. It is literally the only individual influenza fatality counting going on in this country, and while it may miss some cases, it is probably fairly accurate.





The other prime indicator in the US is the 122 MRS, which monitors the number of pneumonia & Influenza deaths in 122 American cities. 


While this monitoring won’t pick up every death, we have good baselines with this model, and should be able to monitor the relative strength of the epidemic outbreak.


We’ve other metrics, of course.  The number of P&I hospitalizations, outpatient visits for ILI (Influenza-like-illness), and the like.  But the one metric every one looks to – the number of deaths caused by this virus –  is the hardest to measure.


Complicating matters is the fact that (fortunately) this virus appears to be causing a high morbidity-low mortality pandemic. 


In other words – it causes a lot of illness - which stresses our health care delivery system and economy,  but relatively few fatalities.  So far, anyway.


Deaths, in all fairness, are not the only measure of a pandemic.


While the surveillance and reporting of influenza deaths in the US may seem less than optimal, when compared to most of the rest of the world, we are very diligent in these matters.


In many nations, medical care and surveillance is rare or non-existent. People die, and are quickly buried, without a cause of death being established. 


In Sub-Saharan Africa and parts of Asia, thousands die every day from AIDS, Tuberculosis, Malaria, contaminated water, hunger, tropical diseases and poverty. 


No one is counting how many were hurried along this dismal path by influenza.


All of this means that the numbers being quoted by the WHO and individual countries (including the US) are practically meaningless.


Worse, they are highly misleading.  


The truth is, we will never know with any precision how many lives this pandemic will claim.  Just as we have no clear idea of how many died in 1968, 1957, or 1918.  


Undoubtedly, over the next few years there will be studies, mathematical models, and estimates proffered by scientists from all around the world. They will be hotly debated in the science journals, among bloggers, and in the halls of academia.


At some point, a consensus will be reached, and a number (probably a broad range) will be announced.


Only then will we have some idea how this pandemic compares to 1968 or 1957.


phytosleuth said...

"Why? Because we aren’t trying to count the number of deaths anymore, and even when we were - back in the summer - we weren’t doing a particularly good job of it."

Did you write this correct? We aren't counting CASES but we are counting DEATHS yes?

Just checking

FLA_MEDIC said...

I'm afraid it's true . . .

While the CDC has many different measuring tools for this pandemic (122 MRS, ILINet, Pediatric Mortality reporting, among others) none of them attempt to count every death in the country due to novel H1N1 .

It is - and always was - an impossible task to try to get any kind of accurate count. Even here in the US.

The same sort of metrics used every year for seasonal flu are being used (with some enhancements) to track H1N1.

And the best we can do with seasonal flu is make an estimate each year, based on sampling, and mathematical models.

Any counts you see are partial counts at best, and may include P&Is due to other causes than novel H1N1.

There are genuine limits to our surveillance and reporting ability.

Not a slam against the CDC, just the way it is.