Antibiotic prophylaxis isn't needed for removal of below the knee orthopedic implants?

Wow, it has been wicked cold this week and it's only going to get colder. It's so cold that I stayed inside and read JAMA RCTs instead of racing to the mall and fighting for discounted gift wrap. Besides adding to my ID knowledge, perhaps this latest polar vortex is also behind the reduced flammability of the ID profession? One can only hope.

The folks that follow me on twitter know the real reason I'm staying current on JAMA studies is that I've recently accepted a position as an Associate Editor for a new JAMA journal called JAMA Network Open. This open-access journal will begin accepting manuscripts in early 2018. Get those fingers typing - one way to protect yourself from frostbite...

In the Boxing Day issue of JAMA there was a very nice multicenter, double-blind RCT comparing surgical site infection rates post removal of below-the-knee orthopedic implants in patients receiving 1g cefazolin vs saline placebo. The 470 randomized patients were from 19 hospitals in the Netherlands and patients were excluded if they had active infection, fistula or were receiving antibiotics. Outcomes followed CDC definitions. Implant removal is considered a clean procedure with expected SSI rates of 2 to 3.3%, so apparently antibiotic prophylaxis isn't indicated; although reported SSI rates have been higher in removal vs implantation procedures, so some recommend prophylaxis.

Spoiler alert: The study was negative. 13.2% of patients in the cefazolin arm and 14.9% in the placebo arm developed SSI, (absolute risk difference, −1.7 [95% CI, −8.0 to 4.6], P = .60). Results below in Table 2. Thus, with a negative study, I headed to the sample size calculations section where the authors stated that they powered the study with an estimated SSI rate of 3.3% in the cefazolin arm and 10% in the placebo arm based on the SSI rates in clean-contamined procedures and recent Dutch retrospective studies, respectively.

Few thoughts. First, this is an underpowered study. It's true that they hit their target sample size, but their estimates were completed using rosy expectations for the benefits of cefazolin and were not selected based on clinically meaningful reductions in SSI. Many might think a 2% absolute reduction in SSI is clinically meaningful. Second, the authors suggest that the high rates of SSI might have resulted from very low thresholds for starting antibiotics if there was "the slightest suspicion of a SSI." Since CDC definitions define SSI based on receipt of antibiotic treatment, this behavior could have biased the rates. Finally, deep SSI rates were 0.4% (1 patient) in the cefazolin group and a far higher 2.9% (7 patients) in the placebo group, (absolute risk difference, −2.5 [95% CI, −5.7 to 0.4]). Since the study was powered for the primary outcome, all SSI, not much was made of the big difference in deep SSI. 

The end result might be disappointing but this is no discredit to the authors and clinicians behind the study - RCTs are very hard to design and implement  - thumbs up for all their efforts. With that said, I would prescribe cefazolin as a peri-operative antibiotic during implant removal below the knee since a 2% absolute reduction in all SSI and a 2.5% reduction in deep SSI are both clinically meaningful benefits. I will then wait for another larger study powered using clinically meaningful SSI targets, including deep SSI.

The smoldering dumpster

I’m a bit delayed this year in commenting upon the ID Match results—go here for our prior posts on this topic (and the broader issues affecting recruitment into our specialty).

IDSA has a good summary of the results, and the figures below are taken from that article. The overall message is: the dumpster fire is no longer raging, but the dumpster is still smoldering! We’ve basically held steady since the new “all-in” Match started last year, with similar percentages of programs and positions filled. 

How to interpret the numbers? I think the “all-in” rules have reduced some (most?) of the outside-the-match ‘strategery’ that some programs and applicants were practicing. Thus after a couple years of “all-in”, we have a more accurate picture of the supply-demand relationship for ID training. This picture is far from pretty—a third of programs are going unfilled, representing one in five of our training spots. Clearly, “train longer to make less” is still a difficult reality to overcome, even for a specialty as fascinating and fulfilling as ID.

So we have a lot of progress to make, and it will have to be made against some pretty stiff headwinds. Easily lost in the numbers is the substantial proportion of positions filled by international medical graduates. This is a great thing in my view, bringing diverse experience and perspective to our programs—but it also makes demand for ID training highly vulnerable to corrosive political forces that may make it less inviting to come to the U.S. for training and employment. If IMG numbers fall, the dumpster fire will rage anew.

Finally, the political landscape will undoubtedly also shape the U.S. healthcare system in ways that are unpredictable, but which could reverse some of the trends favorable to ID (e.g. focus on population health and value, with requirements that promised to provide more fulfilling job options for ID—stewardship and infection prevention among them). The strong anti-regulatory mood of the current administration, along with increases in the uninsured population, could reduce incentives for healthcare systems to invest heavily in quality and safety. 

To sum up, this year’s match should serve as a continued call-to-action, as we still have huge challenges ahead as a specialty.

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Holiday gift idea!

Anyone who practices hospital infection prevention knows how many “data gaps” exist—gaps that make it very difficult to decide which approaches ought to be implemented in your own facility. Should we institute a no-touch disinfection technology? Implement universal decolonization? Use gowns and gloves for all ICU patients? Spend money on an automated hand hygiene monitoring system? Establish a bare-below-the-elbows attire policy? Invest in antimicrobial impregnated textiles (curtains, scrubs, etc.)? Recommend probiotics for selected patient populations?

In the absence of definitive studies, we want carefully considered opinions from smart people who have a wealth of experience in infection prevention. Right?

So if you’re looking for holiday gift ideas for your favorite hospital epidemiologist or infection preventionist, check out this new textbook: “Infection Prevention: New Perspectives and Controversies”, edited by our friends Gonzalo Bearman, Silvia Munoz-Price, Dan Morgan and Rekha Murthy. The text is a nice companion to this blog—in addition to covering all the above questions (and more), the chapters are generally concise, well-written and appropriately referenced. The emphasis is not on being encyclopedic, but on addressing the top-of-mind issues that hospital epidemiologists and infection preventionists deal with most often.