Can sutures get wet? Prospective randomised controlled trial of wound management in general practice
BMJ 2006; 332 doi: https://doi.org/10.1136/bmj.38800.628704.AE (Published 04 May 2006) Cite this as: BMJ 2006;332:1053
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I read this article with much interest because in Thailand, where I
practise, any kind of wounds are left clean and dry. The principle of
"keeping the wound absolutely dry" has been taught and well ingrained into
the practice of majority of medical personels since Joseph Lister's germ-theory days.
Your paper is a welcome finding for which I have been looking to backup
my long-lasting believe that wound care after primary closure should not
include "absolutely dry" principle because the epithelialization is
usually completed in 24 to 48 hours. The lingering doubt in my mind after
reading your article is whether stitch absecess is a problem because that
is the only route where bacteria can enter. Since you excluded that from
the infection tally I am wondering whether you have recorded it and if so
would you share with me the stitch abscess rate? Yours can be one of a
landmark article which save a lot of trouble and expense for the patients
in wound care in my country and elswhere. Would you kindly respond to my
query via e-mail: narisj@hotmail.com. Thank you.
Competing interests:
None declared
Competing interests: No competing interests
The picture on the cover of your issue of the 6th of May shows a
badly sutured wound. If this picture is provided by the authors of the
paper published in the same issue on Page 1053 pp, one is not surprised to
hear that their infection rate is 8-9%.
Tick suture material, traumatic suturing, tightness of closure, blood
smeared over the skin and blood clots surrounding the sutures are all risk
factors for infection. This wound would benefit from washing.
As far as the research question is concerned: properly sutured
wounds, small or large, benefit from daily showers –showers can be
considered as homeostasic with regard to skin ecology.
Competing interests:
None declared
Competing interests: No competing interests
As a surgical trainee I often have opportunity to advise patients on
the care of their wounds after surgery and therefore read this article
with interest. I was trying, in good Evidence Based Medicine fashion, to
assess whether the results of this trial were valid by looking at whether
all patients were analysed in the groups to which they were randomised. I
seem to have found a discrepancy between results and abstract, but am open
to correction if I have misread the paper!
The authors state that all analyses were based on the intention to
treat principle. However, the results section of the paper states that 450
patients were randomised to the wet group and 420 to the dry, but the
abstract describes the number of participants (the 857 who were followed
up and therfore analysed) as 442 randomised to the dry group and 415 to
the wet group. It would appear that more patients were analysed in the dry
group than were randomised to it.
Either there is an simple error in the text (and the wrong number
attributed to each group in the first paragraph of the results section),
or else the results were not analysed on an intention to treat basis.
Either way, further clarification is required before the results of this
trial can be accepted.
Competing interests:
None declared
Competing interests: No competing interests
Thanks (Dr Ada Majd) for your kind response. In answer to your
questions
1)All patients presenting for a minor skin excision were eligible. This
included all patients who had any skin lesion excised and repaired by
direct sutures over the study period. Size and number of sutures were not
measured or used in this definition. Skin flaps or two level procedures
were excluded.
2)All wounds were clean.
3)We did not study any wounds involving genital or GI tracts.
4)All infections recorded fitted the previously cited definition of
superficial surgical site infection. There were no deep or more
complicated infections
Competing interests:
None declared
Competing interests: No competing interests
When we originally submitted the paper we had treated the study as an
equivalence study and had presented two sided confidence intervals of
0.042, 0.033. However the editors of BMJ suggested that it was actually a
non-inferiority study, suggesting: "If it is truly a "non-inferiority"
trial please calculate 1 sided confidence intervals, where the other side
will stretch to infinity. This will in fact have the effect of narrowing
the confidence interval on the non-inferiority side compared to what you
present at the moment."
We therefore calculated one sided confidence intervals as suggested.
We appreciate the advice and comments of our colleague, and wonder if
next time we should question the advice that we are given, even if it
comes from reviewer's of high profile journals. Ultimately we have to take
the responsibility for the text as it is published.
We decided prior to the study that, with an anticipated infection
rate of 5%, we would consider an increase of infection rate of 5%, i.e. an
infection rate of 10%,as clinically significant. I agree that the
threshold of a doubling of infection rate seems quite large, and we did
discuss this, however we decided as a group that this was what we would
consider to be significant to us in our clinical practice.
Our pilot study included facial excisions, which have been shown to
have a lower incidence of infection (1), while facial excisions were
excluded from the main RCT, and this may explain why our infection rate
was higher than anticipated.
(1)Sylaidis P, Wood S, Murray DS. Postoperative infection following
clean facial surgery. Ann Plast Surg.1997 Oct;39(4):342-6
Competing interests:
None declared
Competing interests: No competing interests
I read this article with a lot of enthusiasm and would like to share
my personal experience regarding this matter. When I was working as a
house officer in Professorial obstetrics and gynecology unit in Colombo,
my consultant always used to advice the post operative patients to wash
their tummies with clean water. Initially I was little concerned about
this. But after some I realized that I will do much better to the patient
and I noticed that wound healing is enhanced by this probably due to the
cleaned and healthy tissues.
This was clearly evident in obese patients whose pendulous abdomens
will cover the pfanenstiel incision in the lower half of the abdomen. So I
also started advising the patients to wash their tummies with water and
modified my consultants practice by asking them to use soap also. This
gave me the same results without any trouble.
So I think that the practice is beneficial not only to superficial
incisions but also to larger incisions.
Competing interests:
None declared
Competing interests: No competing interests
Statistical analyses should illuminate the results of research, but
those presented here serve to obscure.
The authors give a 95% confidence interval for the difference in the
proportion infected as infinity to 0.028.
This must be wrong.
A confidence interval is a range of values which we estimate to
contain the population value. The population value in this case is the
difference, uncovered wounds minus covered wounds, in the proportion
experiencing infection. First, it should not include 0.05 or 5 percentage
points, because the difference is stated to be significantly below 0.05.
Should it therefore be minus infinity to 0.028?
Was a minus sign omitted? Second, the difference between two proportions
has to lie between -1.0 and +1.0, because each proportion has to be
between zero and one. It cannot be larger than 1.0 or less than -1.0.
The one-sided confidence interval should be -1.000 to +0.028.
The authors could have presented the ordinary two-sided 95%
confidence interval, which for the difference between proportions
infected, uncovered minus control, -0.042 to +0.033, or -4.2 to +3.3
percentage points. An alternative would be to give the risk ratio for
infection, uncovered over covered, which I estimate to be 0.95, 95%
confidence interval 0.61 to 1.47. I think that either of these approaches
this would have been more meaningful
to many BMJ readers. (The figures are approximate, because the actual
numbers of subjects used in the calculations are not given in the paper.)
The one-sided significance test tests the null hypothesis that the
difference is greater than or equal to 0.05 or 5 percentage points.
Anything less than this doubling of the proportion infected is regarded by
the authors as equivalent, but no attempt is made to justify this view and
it is not mentioned where the test is presented in the abstract. It seems
to my ignorant mind to be pretty big for the treatments to be equivalent.
Competing interests:
None declared
Competing interests: No competing interests
Every surgeon is apprehensive about skin wound closure. Apart from
avoiding discomfort to patient, we feel that the skin scar is a mirror of
all the surgery.
It has been customary to keep even smallest sutured wounds dry, to prevent
any infection in scar.
I have a moderate practice in India. I perform about fifty laprascopies a
year, for diagnosis and tretment of infertility and tubal ligation. I
close abdominal wound with a deep mattress suture, to close sheath at the
same time, with thread. My primary trocar is 8 mm, and other are variable,
5.5 to 8 mm, one or two.
After first 5 years, i started allowing my patients to take a bath over
bandaid type dressing, about 24 hours after surgery. The reasons were
patients are keen to have a morning bath, without which they cannot carry
out daily religious rituals and are not supposed to cook. I wanted to make
them fell 'normal', as early as possible.
I have been carrying out this practice for last 20 years, and have never
repented. There have been NO incidences of wound sepsis.
Competing interests:
None declared
Competing interests: No competing interests
To The Editor,
I read with interest the article on surgical site infection (SSI)1.
It is a randomised controlled trial (RCT) which is level I evidence 2 but
the conclusions are not justified for the following reasons
1. This is a study on clean wounds where the accepted infection rate is
<5 % 3. In the control group of this study the infection rate is 8.9%!
2. Pilot study performed showed an overall infection rate of 5.7% 1 which
is more acceptable and the sample size calculation was based on this
result. As the control group in the RCT had a higher infection rate
(8.9%), the conclusions based on this study is not valid
This paper does not add anything new to what is already known about
SSI in the different wounds but shows the typical flaws when performing a
RCT and does not approve or disapprove the hypothesis.
Competing interests: None declared
References:
1. Heal C, Buettner P, Raasch B, Browning S, Graham D, Bidgood R et
al. Can sutures get wet? Prospective randomised controlled trial of wound
management in general practice. BMJ 2006;332:1053-6.
2. http://www.cebm.net/levels_of_evidence.asp#levels
3. Culver DH, Horan TC, Gaynes RP, Martone WJ, Jarvis WR, Emori TG et
al. Surgical wound infection rates by wound class, operative procedure,
and patient risk index. National Nosocomial Infections Surveillance
System. Am.J.Med. 1991;91:152S-7S.
Competing interests:
None declared
Competing interests: No competing interests
correction to abstract
In response to Dr Moffat: Thankyou for identifying this problem (we
appreciate your diligence), it is indeed a mistake in the abstract. To
clarify, 450 patients were randomised into the wet group and 442 completed
the randomisation process, 420 patients were randomised into the dry group
and 415 completed the randomisation process. Unfortunately figure 1 has
been incorrectly reproduced as figure 2, and figure 2, the consort
flowchart, which would have clarified this issue, has been omitted. This
omission was corrected in the online first version of the paper but
unfortunately appears to have been reproduced in the electronic edition.
In response to Dr Loefler: No, indeed this is not one of our sutured
wounds. The authors appreciate your concern regarding our suturing
techniques but would like to reassure you that any concern is unwarranted.
Competing interests:
None declared
Competing interests: No competing interests