UPDATED: See note at bottom
# 3361
It’s a phrase that we almost always hear when flu fatalities are reported. That a patient `may have had underlying medical conditions that contributed to their death.’
Today, during a teleconference by the CDC, Dr. Dan Jernigan gave us a bit more detail on this oft repeated claim.
When asked, he stated that about 40% 70% (see note at bottom) of those hospitalized in the US (that they have data on) have had significant underlying medical conditions; with asthma, diabetes, compromised immune systems, or heart disease leading the pack.
Unusually for influenza, the vast majority of the 1600 hospitalizations so far have been in those under the age of 50.
The reasons for this aren’t really clear.
It is thought that people over the age of 50 may have some degree of pre-existing immunity from a variant of H1N1 that circulated in the late 1950’s.
There isn’t a whole lot of science (yet) to back that up. But scientists are investigating.
Another theory involves a more robust immune response from those under the age of 50, which has resulted in a more severe illness.
This harkens back to the discussions we’ve had in the past on the `cytokine storm theory’, which postulates that younger, stronger immune systems can go into overdrive when confronted by a novel virus, literally killing the host they normally protect.
Unfortunately, our understanding of the immune system is far from complete, and so while we can observe reactions – including what we call a `cytokine storm’ – we aren’t very good at explaining them.
The CDC lists the following groups as being at `higher risk’, due to age, or medical conditions.
- People who are over 65, under age 2, or pregnant
- People with chronic lung problems, such as asthma or emphysema
- People with chronic heart, kidney, liver or blood disorders
- People with neurological disorders that can cause breathing problems
- People with diabetes
- People whose immune systems are weakened due to illness or medication
- People under 18 years who are on long-term aspirin therapy
What this tells us is that, indeed, some underlying conditions do seem to result in a higher risk of complications from this flu, but 30% of those hospitalized had no obvious underlying conditions.
And the number of people who fall into the above groups is pretty high. There are more than 30 million people with asthma in the United States, 23 million Americans with Diabetes, and between 6 and 7 million pregnancies each year.
Last night, Helen Branswell of the Canadian Press wrote on this subject (hat tip Crof at Crofsblog), which is well worth reading in its entirety.
Risk factors for severe swine flu a wide umbrella under which many stand: experts
TORONTO — Whether speaking of a 58-year-old man or a 38-year-old woman or a little boy of nine, officials announcing swine flu deaths are almost always quick to note "underlying health conditions" may have contributed to the fatal outcome.
Asthma, heart disease, diabetes, maybe even obesity are among the conditions used to help explain why swine flu infection is hospitalizing and killing younger people, people who would be expected to make a full recovery from seasonal flu.
It could create the impression that only the sickly are dying from the new H1N1 flu virus - a claim no one is making. To the contrary, many, including the World Health Organization, say between one-third and one-half of swine flu deaths have occurred in people who were previously healthy.
But how healthy is previously healthy? The answer depends on who you ask.
We need to remember that there have been hundreds of thousands (maybe millions) of infections in the United States -and so far - only a couple of thousand serious illnesses reported.
This flu certainly isn’t benign, but it isn’t a 1918-style killer either.
It does, however, deserve our respect and our attention.
Bad outcomes are no less tragic to the people they affect simply because, statistically, this isn’t a severe pandemic.
UPDATE: In the transcript from today’s briefing, a correction was made to the percent of hospitalized patients with `underlying conditions’.
I’ve reproduced that portion of the (corrected) transcript.
Dan Jernigan: Your question is, what numbers of individuals that are hospitalized have underlying diseases, and
about 40% or soabout 70% (this is the corrected percent of hospitalized patients with underlying health conditions) have some kind of underlying disease. The most predominant of that is asthma. The second being diabetes.
Immunocompromised status, either through cancer chemotherapy or other compromising conditions is about 13%. And chronic underlying heart disease.
The things that we see normally as underlying diseases that are associated with increased influenza risk are the same that we're seeing with H1N1.
Having done a good deal of public speaking myself, I know how difficult doing Q&A sessions can be. Particularly when dealing with very technical issues.
Misstatements are bound to happen.
Thankfully, the CDC quickly discovered mistake and corrected the record.
