In May of 2012 the NEMJ published an article about the cardiac risks of Azithromycin. This fake science was the base for recent decision of the FDA to issue a black box warning, which in my opinion was an overboard and wrong move. Last year I replied with this editorial, which I admit, it was a little harsh with a touch of my usual sarcasm, that's probably why it didn't get published. Nevertheless, I just want to add it to my blog for those who want read and think outside this black box (warning).
First, read it from the NEJM site:
http://www.nejm.org/doi/full/10.1056/NEJMoa1003833?query=emergency-medicine
According to the
authors, it seems
like you are almost
2.5 times more
likely to die a
cardiovascular death
after a course of
"Azithro" than you
are after taking 7
days of Amoxil, and
almost 3 times
compared to no
antibiotics at all.
Which means that
even amoxicillin has
a hazard ratio of
0.5 compared to not
taking any
antibiotics.
However... Let's
put this in
perspective, shall
we? Using the numbers
provided in the
result section, you
need to prescribe
1,000,000 Z-packs to
kill 47 patients
with low
cardiovascular risk
and 245 with high
cardiovascular risk.
That means that even
in the worse case scenario, the number
needed to kill by
one course of
azithromycin is 1
per 4081 compared
with 1 in 10,202 of
amoxicillin. Hmmm... Do you
want a more
ridiculous number?
- OK. Assuming that
you prescribe
Azithromycin once a
day every day of the
year; you need to
practice for 11
years, non-stop and
with no days off to
kill one patient
with high
cardiovascular risk and 58 years for the low cardiovascular risk patients.
Amazing, isn't? -
To me this doesn't
sound too bad when
compared with the
27% mortality rate
of sepsis with
severe pneumonia or
with other therapies
we use, like warfarin
that clearly has a
higher risk of harm
associated with it.
What I would like to
see is more details
about the high risk
patients. As
statisticians say
"The devil is in the
details". In the first place, we don't give antibiotics to healthy people (so I hope), and using healthy patients as denominator just doesn't seem right. Then, there is the fact that
Azithro is
considered a
"stronger"
antibiotic compared
to amoxi being a
better choice for
sicker patients. And why is it that Azithromycin is in the guidelines for the treatment of pneumonia and not amoxicillin? Was
the choice of
Azithromycin a
marker or more
severe disease and
therefore prescribed
to sicker patients
who had more risk of
death regardless of
the antibiotic
choice? - I don't
know. This article
doesn't answer that.
There is no question
that antibiotics
(and for that
matter, any
medication) will
hurt some patients,
that is just
reality. Some will
have minor problems
and some others will
even die as direct
consequence of the
drug. About 10 years ago my cardiology professor and I
wrote an editorial
about several types
of medications and
the risk of CV death
by long QT syndrome
(Headache. 2003 Jul-Aug;43(7):809-10.), and even
then, we found that
commonly prescribe
drugs will have that
effect in
genetically
susceptible
patients. It has to
do with some weird
channelopathy of the
slow potassium
channels in the
myocardium and these
folks will just drop
death from a
malignant
dysrrhythmia. This
effect is
significantly
increased with
certain types of
medications and
macrolides are one
of them. Thankfully,
the susceptibility
due to genetic
predisposition is
very rare, so rare,
that we don't routinely screen
patients for
channelopathies, do
we? However, a sick
heart is a sick
heart regardless of
the cause and these
patients will have
higher mortality
even if you give
them gummy bears for
their presbyopia and
then an article will
be published urging
a black box warning
for gummy bears.
The bottom line is
that the possible
harm (extremely
unlikely) most be
weigh with benefits
(more likely) and to
ask the questions: Is the patient at risk? Taking other QT prolonging meds? Is there history of sudden cardiac death in the family? - In the very few cases with a positive answer, a screening EKG should suffice to make your antibiotic choice.
Finally, this black box warning forces the question... Is the FDA black boxing azithromycin b/c a new "safer" macrolide will be soon introduced to the market in-sync with the Azithromycin patent expiration? Hmmmm. I know I am being cynical... :p
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