Wednesday, September 12, 2012

Does the timing of appendectomy influence the wound infection rate?

“Yes,” says a large review of a single institution’s experience with appendectomy for acute appendicitis.

The study looked at over 4500 patients who underwent appendectomies over the 8-year period between 2003 and 2011. The main findings of the study were that patients who developed surgical site infection (SSI) had a significantly longer delay in going to the operating room. Time to appendectomy was defined as the time the patients were admitted to the surgery service until they reached the operating room (OR).

Patients who developed infections were taken to the OR after a mean of 14 1/2 hours compared to 11 hours and 45 minutes for those who did not, which was a statistically significant difference, p = 0.013.

The delay in taking patients to the operating room did not lead to more perforations. However, the rate of perforation in this series was rather high at 23%.

The abstract concluded, "prompt surgical intervention is warranted to avoid additional morbidity in this population."

Since this paper supports my bias about performing appendectomies as soon as the diagnosis is made (as I have previously blogged), I was hoping that its findings would be valid. Unfortunately, that is not the case. The paper is not as convincing as the abstract.

The authors state that surgeons and operating room personnel are in the hospital 24 hours a day. It is not clear why patients’ operations were delayed so long. There is no mention of whether the patients received antibiotics while they were waiting. If more patients who did not suffer SSI's had received antibiotics, the paper’s results could be misleading. If you look at the mean difference between times to the operating room for non-infected versus the infected patients, you will note that it is a little less than 3 hours, which really is not that long.

Another issue is that only 41% of the patients underwent laparoscopic appendectomy. In my practice and that of most other surgeons, 90%-95% of patients with appendicitis are operated on via the laparoscopic approach. Laparoscopic appendectomy is known to have a lower wound infection rate than open.

The mean hospital length of stay for the non-perforated patients was 3.4 days, highlighting the outdated nature of the information. Most patients with non-perforated appendicitis are discharged within 24 hours of surgery in 2012.

However the most important problem with the paper has to do with the key factor that the paper emphasized; that is time. Not only was the duration of the patients’ symptoms prior to arrival at the hospital unknown, the authors also did not account for the length of time that the patients spent in the emergency department. If diagnostic CT scans, which are done about 90% of the time for appendicitis, were performed, the patients probably spent at least 6 hours in the ED.

It does not stand to reason that a less than 3-hour average difference in taking patients to the operating room when the preop duration of symptoms is unknown could possibly be significant. And 11 hours and 45 minutes to get a patient to the OR does not define “prompt” for me.

Bottom line: As I have said before (here and here), you have to read the entire paper and not just the abstract.


Dr Skeptic said...

Thanks for doing what many readers who only skim abstracts don't do: critically appraise the article. Biases like those you point out are rife in studies of this nature where data from a large retrospective cohort are crunched until something significant comes out of them.

There ought to be a law against conclusions that are not adequately supported by the findings of the study.

Skeptical Scalpel said...

Thanks for the comments. I agree with your last sentence. At least there should be a law that the abstract should have something to do with the paper.

Unknown said...

Perhaps someone publishing the article should review the abstract and article and, I don't know, suggest edits: hey, that's a good idea there should be a job like that perhaps "editor" or "reviewer" pr something!

Skeptical Scalpel said...

Pik, that's a great comment. It is hard to understand why that isn't done.

Anonymous said...

In this day and age when anything and everything must be published to add another line in your CV it's becoming harder to find diamonds of knowledge amongst all the crap

Skeptical Scalpel said...

I agree. It's kind of sad.

bigjimricotta said...

I agree with skeptical's bias that the appendectomy should be done as soon as possible when the diagnosis is made. Unfortunately, the trend now is surgeons are now booking patients who have the diagnosis made at midnight for 6am.

Skeptical Scalpel said...

Thanks for commenting. Even if there is no outcome difference between immediate and delayed surgery, what about the unnecessary pain that the patient has to go through while waiting overnight for the case to be done? In my experience, it's hard to muster the OR team at 6 am. The overnight crew drags their feet until the day shift arrives. Now you are bumping someone from the elective schedule.

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