[Matthias.Maiwald@KKH.COM.SG Subject: Misleading Systematic Reviews on Surgical Skin Antisepsis MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Message-ID:]

Dear Group,

I would like to follow up on this previous thread and point out that our
letters to the editor have now appeared.

http://onlinelibrary.wiley.com/doi/10.1002/bjs.7446/abstract

http://www.jstor.org/stable/10.1086/659253

They were accompanied by letters from other groups expressing effectively
the same concern.

The original authors’ reply was grossly inappropriate in terms of being
misleading and distorting the facts. I will not go into detail here, but I
can provide the reasons/rationale for this assessment if this is required.

This is an issue of serious concern, as I am more and more seeing
statements along the lines that “there is evidence that chlorhexidine is
superior [to anything else]”. At the same time, if taken literally and if
only chlorhexidine (in aqueous solution) would be used for superficial skin
preparation, then one would put patients at serious risk of surgical
infection.

I think the infection control and infectious diseases community need to be
aware of this.

Best regards, Matthias.

—
Matthias Maiwald, MD, FRCPA
Consultant in Microbiology
Adj. Assoc. Prof., Natl. Univ. Singapore
Department of Pathology and Laboratory Medicine
KK Women’s and Children’s Hospital
100 Bukit Timah Road
Singapore 229899
Tel. +65 6394 8725 (Office)
Tel. +65 6394 1389 (Laboratory)
Fax +65 6394 1387

Matthias.Maiwald@
KKH.COM.SG
Sent by: AICA To
Infexion AICALIST@AICALIST.ORG.AU
Connexion cc
Subject
Misleading Systematic Reviews on
Surgical Skin Antisepsis
17/12/2010 08:45
AM

Please respond to
AICA Infexion
Connexion

Dear Group,

I would like to follow up on previous discussions on pre-surgical skin
antisepsis and point out two highly problematic systematic reviews that
have recently appeared (almost simultaneously).

http://www.ncbi.nlm.nih.gov/pubmed/20878942

http://www.ncbi.nlm.nih.gov/pubmed/20969449

These are two systematic reviews of what is described as comparisons of
“chlorhexidine versus povidone-iodine” for preoperative skin antisepsis.
The unanimous conclusion in both articles is that chlorhexidine is the more
effective antiseptic in preventing surgical site infections (SSIs) than
povidone-iodine. However, the interesting thing when reading both articles
is that the majority of studies that were analysed used alcoholic
chlorhexidine versus aqueous povidone iodine. Of course, both chlorhexidine
and povidone-iodine are available as both alcoholic and aqueous
formulations. The aqueous formulations have only one, the alcoholic
formulations have two active ingredients in each. That means, the authors
of both reviews have mainly compared formulations with two active
ingredients (alcohol and chlorhexidine) versus formulations with only one
active ingredient (povidone-iodine). Yet, both reviews unanimously and
solely attribute the positive study outcomes to chlorhexidine, and there is
no word that the alcohol could have contributed to the prevention of SSIs.
That means, the alcohol has been completely ignored, despite good evidence
from microbiological studies that alcohols are generally about a factor 10
more active than chlorhexidine when used on its own.

I have joined with two other colleagues (one from Switzerland, one from
Austria) and we have written letters to the editor to both journals,
disputing these conclusions.

This is an interesting and possibly dangerous misconception. There are
indeed a number of recent publications describing the benefits from the
combination of alcohol and chlorhexidine (note that extensive studies on
these antiseptics have already been done in the 1970s). We are seeing a
number of recent statements on Infection Control websites (e.g. Infection
Control Today), e-mail discussion forums and a few journal articles where
the benefits of this combination is solely attributed to chlorhexidine, and
the alcohol in the combined formulation is completely ignored. The question
is often something like: “Has chlorhexidine been used for skin antisepsis
according to the evidence base?” It appears that the alcohol in this
combination is regarded by some writers/authors as a mere carrier substance
for the chlorhexidine that does not participate in the disinfection
process. (For example, there is a posting on Infection Control Today that
looks into the issue of whether people have followed the evidence base and
used chlorhexidine for skin antisepsis, just barely mentioning the alcohol
on the side). The problem is that this is scientifically and medically
grossly wrong, and there is even a danger that some people reading such
statements might indeed use chlorhexidine on its own for superficial skin
antisepsis, and thereby put patients at risk. It is also important to note
that the combination of alcohol and povidone iodine has microbiologically
very similar activity to alcohol-chlorhexidine and should not be wrongly
dismissed based on conclusions derived from aqueous povidone-iodine (the
latter has been known to be inferior for decades).

We are currently considering if we can raise this with a few professional
organisations, such as perhaps SHEA (Society for Healthcare Epidemiology of
America), ESCMID (European Society for Clinical Microbiology and Infectious
Diseases), AICA and/or ASID to prevent this misconception from spreading
even further.

I think that based on the pervasive and current nature of this
chlorhexidine misconception I need to share this with the group.

Best regards, Matthias.

—
Matthias Maiwald, MD, FRCPA
Consultant in Microbiology
Adj. Assoc. Prof., Natl. Univ. Singapore
Department of Pathology and Laboratory Medicine
KK Women’s and Children’s Hospital
100 Bukit Timah Road
Singapore 229899
Tel. +65 6394 8725 (Office)
Tel. +65 6394 1389 (Laboratory)
Fax +65 6394 1387

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The information contained in this e-mail or in any attachment is
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e-mail in error, please notify the sender immediately by e-mail and delete
all copies of this e-mail. All opinions, conclusions and other information
expressed in this e-mail that are not of an official nature shall not be
deemed as given or endorsed by KK Women’s & Children’s Hospital.

Insofar as this e-mail contains any medical opinion or advice, the medical
opinion or advice is premised solely on the extent of medical information
available to the writer of this e-mail and, where applicable, qualified by
the lack of direct physical assessment and personal evaluation of the
patient. Any medical opinion or advice expressed in this email does not
necessarily represent the views of KK Women’s & Children’s Hospital.

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