Safer.

AHRQ.

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.

Should surgeons be allowed to prescribe antibiotics without assistance?

It's the end of a long day on the ID consult service. You and the team have decided to recommend switching antibiotics on a post-op cardiac surgery patient since the S. aureus susceptibilities have returned and you'd prefer cefazolin over vancomycin for her MSSA bacteremia. The team text messages the primary surgical team and the intern meets the team in the ICU. You overhear the ID fellow's discussion with the surgical intern, who appears to not know the patient and who can't get approval from the senior resident, CT surgery fellow or the attending to make the antibiotic change since the whole team is scrubbed in the OR.

The above scenario is all too familiar to those who practice infectious diseases, and to be fair it could apply to other procedure-based subspecialties. But the question arrises, if only oncologists can prescribe chemotherapy, why is it that everyone is allowed to prescribe antibiotics? Is this really what is best for our patients? Yes, this is currently a controversial topic but these are the types of questions we need to ask if we're going to respond to the antimicrobial resistance crisis.

A group of researchers in the UK led by Esmita Charani and Alison Holmes began exploring the effects of culture and team dynamics on antimicrobial prescribing during surgical ward rounds and the results of their ethnographic study left me convinced that we must develop ways to improve antimicrobial prescribing on surgical services.

The research team observed the antimicrobial prescribing decision making of six surgical teams over a 3-month period. These included observation of 30 ward rounds and face-to-face, semi-structured interviews of 13 clinicians (5 consultant/attending surgeons, 3 registrars/residents, 2 nurses, 2 junior doctors/interns and the ward pharmacist). The qualitative analysis identified 4 key themes that influence antibiotic prescribing: (1) working in a constant state of flux; (2) communication jigsaw; (3) delegating antibiotic management; and (4) the need for an intervention. Here are a few quotes from the study:

Constant flux: There is a hierarchy as to who leads ward rounds (WR), but this is a shifting hierarchy whereby people are promoted or demoted from their position based on who is present on the WR...if the surgeon leading the WR is called away, for example to the OR, the line of authority shifts downwards and people must act up, for example the registrar takes on the role of the surgeon, the junior doctor ‘becomes’ the registrar and the medical student ‘becomes’ the junior doctor.

Communication jigsaw: WRs are often rushed, interrupted and dispersed and reconvened because of demands for the senior team to be in the OR. The constant disruption and people leaving and joining the WR means that members of staff will rarely be present for the entire WR. Because of being constantly split between the OR and the ward, communication within the surgical team occurs across different platforms. Key decisions are made, recorded and communicated not necessarily in medical health records but on handover sheets, text messaging, and applications on smartphones (e.g. WhatsApp). On many occasions a patient was thought to be on antibiotics by the team, and after further queries in notes and charts was found not to be on them, and vice versa.

Delegating antibiotic management: Surgeons tended to see the core elements of their role as relating to the surgical management of their patients, a role that is performed in the OR. The lack of priority given to antibiotic decision making is compounded by a lack of expertise, resulting in responsibility for antibiotic decisions being commonly delegated to others.

The need for intervention: The need and expectation to intervene means that often antibiotics are initiated for patients with no or little evidence of infection, but a high plausibility of infection in the minds of the surgeons. This process is rationalized by the surgeons as being an extension of their roles as ‘interventionists’. In the absence of evidence of infection what drives antibiotic decision making is a risk of failure, and a risk of blame. What is considered unique in surgery is that a patient has to be well enough to be able to undergo an operation, therefore any deterioration postoperatively is assumed to be a consequence of the surgery, and the decisions of the surgeon, and not the patient's underlying illness. These concerns drive a more conservative approach to antibiotic decision making leading to unnecessary and prolonged courses of antibiotics.

None of these points will appear very surprising to anyone who has cared for patients on a surgical service. However, the authors are to be commended for the care with which they completed this study and the wonderful structure they provided to the domains that influence antimicrobial prescribing. I agree with their assessment that "there is a need to explicitly assign the responsibility for antibiotic management of the surgical patient to a responsible, individual with necessary expertise... Diagnosis and treatment of infections is a specialty that requires expertise and training, therefore this is an opportunity to develop, with support from specialist microbiology laboratory and staff, a role for a clinician(s) responsible for perioperative antibiotic management. This will help to strengthen the antibiotic management for surgical patients and has the potential to facilitate continuity of care and to help overcome the substantial gaps in communication that have been identified in this study...The time is right to question whether we need to address the gap in antibiotic prescribing for surgical patients by developing this specific perioperative clinician role to manage infections. This is of critical importance considering the rising challenge of antibiotic resistance in postoperative patients."

The Updated CDC SSI Prevention Guidelines are (Finally) Released: A Marathon in its Own Right

(First, thanks to Dan, Eli, and Mike for inviting me to join the blogging crew.  I hope I can meet their outstanding level of performance, and I promise not to write only about healthcare worker influenza vaccination [but I am sure it may come up now and then!])

Last weekend I ran my first half marathon, the St. Jude Nashville Rock ‘n Roll Half Marathon.  As I ran the race, I went through several stages: excitement combined with anxiety before the start, the adrenaline rush during the first few miles, the sense of accomplishment at mile 6, the shear exhaustion of mile 11, the exhilaration of finally finishing, and then the realization of “what’s next?”

With the much anticipated release of the CDC’s HICPAC Guideline for the Prevention of Surgical Site Infection (which updates the 1999 guideline), I realized the guideline authors may have had the same thoughts during its development that I had during my race.  (Disclaimer: Dan, Hilary, and I served on HICPAC during the development of this guideline).  This guideline is long overdue, particularly with the increased focus on reducing SSIs combined with the advances in SSI prevention over the past decade. The writing group consisted of experts in infection prevention, surgical sciences, infectious diseases, and public health, and they should be lauded for their extremely tireless and dedicated work (which we saw first hand at HICPAC).  Just as with my race, the process was likely exciting, rewarding, exhausting, and, I suspect, at times frustrating.

There are important things to recognize when reviewing these new guidelines, outlined in the commentary by Dr. Lipsett.  First, we must understand the evidence inclusion criteria for each section. For the Core Practices section, only randomized controlled trials and systematic reviews were included.  For the Prosthetic Joint Arthroplasty section, due to a lack of such high level studies in the literature for many of the key questions, other types of studies were allowed.  This resulted in limitations to the scope of the recommended practices and many “no recommendation/unresolved issue” decisions on key questions such as the timing and redosing of antibiotic prophylaxis.  Other key questions never made it that far, reflecting a paucity of science on these topics.  In addition, detailed guidance on implementation is not present in the guideline or supplementary materials.  Hidden in the Supplementary Material, the guideline does note those key practices recommended in the 1999 Guideline that were not included in the update but still apply to the surgical patient today (see pages 41-42).

Despite these limitations, there are some significant advances recommended (Category 1A), including expansion of several key interventions to a broader surgical population:

1) Glucose control (<200 mg/dL) for diabetic and nondiabetic patients

2) Maintenance of normothermia

3) Provision of increased FiO₂ in intubated surgical patients with normal pulmonary function

Traditionally, these interventions have been used in specific surgical procedures, such as colorectal and cardiac surgery.  With the new guidelines, many healthcare facilities will need to broaden these interventions to a wider surgical population.  Importantly, the guideline minimizes the commonly heard refrain of the need for studies in a specific surgical procedure before implementation of an intervention.  The pathophysiology of a SSI is probably the same for most surgical patients, supporting the expansion of these important interventions to a wider population.  In addition, the guidelines now recommend stopping antimicrobial prophylaxis once the incision is closed in clean and clean-contaminated procedures (vs. the tradition of continuing for 24hrs, 48hrs, or until all drains have been removed), an important recommendation in the era of antibiotic stewardship.

Much like running a half marathon, we are now at the finish line and asking the question “[w]hat’s next?”  While the new guidelines advance SSI prevention, there is a clear need for implementation guidance related to the recommended practices (such as from SHEA, APIC and others), research funding to support high-level studies that examine key questions for which there was not an adequate evidence base, and expert direction on those strategies that will never be studied by randomized control trials.  Guideline’s finally out.  Let’s get running!!

SSI Prevention Bundle in Cardiac, Hip, and Knee Surgery - A Home Run

...and I'm being modest...

As I mentioned yesterday, it's really hard to write a post when you've already written the accompanying editorial. Today, I have a taller task - posting on a study led by two close colleagues (and favorite people), Marin Schweizer and Loreen Herwaldt. (COI alert) Fortunately, JAMA Associate Editor, Preeti Malani, has done the heavy lifting with her excellent editorial.

In today's JAMA, Schweizer and colleagues reported the results of an AHRQ-funded trial examining the benefits of an SSI prevention bundle in orthopedic and cardiac surgery. The bundle was outlined in a meta-analysis they published in BMJ two years ago and included preoperative nasal screening for MRSA/MSSA, mupirocin BID and daily CHG baths for 5 days if screen positive and vancomycin added to perioperative prophylaxis if MRSA positive. The quasi-experimental intervention study took place in 20 US hospitals across 9 states with 39 months of pre-intervention SSI rates and 21 months of rates collected during the intervention period.

Overall, the results are impressive (i.e. not modest). First, there was a 42% reduction in SSIs after the intervention was implemented (see Figure, below), despite modest bundle adherence (39% full adherence, 44% partial adherence).

The key finding for me relates to the number of months where there were ZERO SSIs across all 20 hospitals. Looking at the Figure above, you can see that "the number of months without any complex S aureus SSIs increased from 2 of 39 months (5.1%) to 8 of 22 months (36.4%; P = .006 by Fisher exact test)." Seven times as many zero-months in all 20 hospitals. That's not a modest finding. ;)

Key points from the editorial:

"inclusion of patients undergoing emergency or urgent operations, a population recognized as at high risk for SSI, improves the generalizability of the findings."

"the primary study outcome was limited to complex S aureus SSIs, eliminating much of the subjectivity of infection surveillance. Even though surveillance practices varied among participating hospitals, complicated S aureus SSIs are not clinically subtle and can be identified easily by any surveillance system."

and given the modest adherence to the bundle, "Moving forward, efforts to promote and maintain adherence to prevention protocols will remain important"

"The study’s setting is among its limitations. All 20 study sites were from a single health care system with a well-established quality improvement infrastructure - certain factors in this health care system may differ from other clinical settings, including a below-average baseline infection rate. It remains unclear what challenges and barriers may present as this bundle is implemented at other institutions. Further studies in different settings will offer additional guidance."

and my favorite quote:"Although getting to zero is unlikely to be achievable, efforts that move closer to this elusive goal hold tremendous value for clinicians, hospitals, payers, and, most importantly, patients."

My final thoughts:
This is a wonderful study that took many years of planning, hard work and tremendous collaborators, including HCA and Ed Septimus. Congrats to all involved. Not every study is a grand slam, but we'll take a home run for infection prevention.

ECCMID 2015 - "Best Of" Infection Control Literature (Part 1)

Every year it seems that one of us at the University of Iowa is roped into giving one of these "Best of Infection Control" talks at an annual conference. This year it seems that almost all of us have been asked and for some inexplicable reason, we all said yes! I was the lucky one to kick off the 2015 season with this talk I gave last week at ECCMID in Copenhagen. I covered S. aureus, MRSA, VRE, VRSA, surgical site infections and hand hygiene. I look forward to Mike's talk at SHEA. Loren Herwaldt's talk at ICPIC and Dan's talk at IDWeek. On Iowa.

THIS...is what we need more of

A little late on this post, but summer.

There's a new randomized trial published in JAMA that evaluates the efficacy of post-cholecystectomy antibiotics in patients presenting with mild/moderate acute calculous cholecystitis. Upon diagnosis, all patient received amoxicillin+clavulanic acid three times a day pre-operatively and once during surgery. This open-label trial compared patients randomized to 5 days of post-operative antibiotics with the same antibiotic regimen vs. no post-operative antibiotics.  Patients were followed up to four weeks post-operatively for SSI and other infections. In the 414 patients, the infection rate was 15% (31/207) in the post-operative antibiotic group and 17% (35/207) in the no-antibiotic group, in the intention-to-treat analysis. The absolute risk difference was small (+/- 2.0%) and the 95% CI for the difference included zero for all key outcomes in the intention-to-treat analysis including superficial, deep and organ space infections. (Table 3 below)

The study appears to have high internal validity and randomization looks adequate. However, the lack of placebo and a relatively large non-inferiority outcome threshold (11%) are potential limitations. Of course, the study was also limited to amox-clav and perhaps some would favor testing other antibiotic regimens. However, the lack of true difference will hopefully lead to further validation studies or adoption of a no post-operative antibiotic recommendation for this surgical procedure. This study and hopefully more like it are exactly what we need in order to reduce antibiotic exposure in hospitals and subsequent selection of antimicrobial resistant pathogens, including C. difficile. It's great to see important antimicrobial stewardship questions asked and answered.

A bundled intervention to decrease surgical site infections: A Video Abstract

Last week we discussed a recent BMJ meta-analysis of SSI prevention intervention studies in cardiac and orthopedic surgery. Who better to tell you about the important results than the authors themselves. Loreen Herwaldt and Marin Schweizer offer their thoughts. Enjoy!

Save your mupirocin for SSI prevention in cardiac and orthopedic surgery

As our guest blogger, Marc-Oliver Wright, posted last week, widespread use of mupirocin was associated with 400% increase in mupirocin resistance at his hospital. Many are very concerned about widespread and non-selective use of mupirocin as a result of the REDUCE MRSA trial, particularly since the incremental benefit of mupirocin added to CHG is not known. Based on prior studies, it is possible that many of the benefits seen were due to CHG and not necessarily mupirocin.

With that in mind, why should we care about mupirocin resistance? Well, there are instances were mupirocin has more established benefits in the literature and one is in surgical site infection prevention. The issue with most infection prevention intervention studies is that most outcomes like SSIs are rare (fortunately) and research budgets are small, which leads to numerous underpowered quasi-experimental studies. The problem with this type of literature base is that it can lead to unnecessary controversy with clinicians cherry-picking study results to support their specific hypothesis.

To make use of such a literature base and scientifically determine the benefits of nasal decolonization (and other interventions), Marin Schweizer and Loreen Herwaldt at the University of Iowa completed a meta-analysis of SSI prevention intervention studies in cardiac and orthopedic surgery, which was published today in the BMJ (free open access). (COI note: I'm a co-author on the paper and was an independent reviewer/data abstracter) After screening 1423 articles published between 1995 and 2012, they identified 39 studies of moderate to high quality. 17 studies assessed the benefits of nasal decolonization (16 mupirocin and 1 nasal CHG), 15 studied glycopeptide prophylaxis and seven examined the bundle: screening+nasal decolonization+vancomycin). The pooled effects were quite impressive.

Nasal decolonization was associated with a 61% reduction in S. aureus SSIs, a 70% reduction in MRSA SSIs and a 50% reduction in MSSA SSIs. Glycopeptide prophylaxis was associated with a 60% reduction in MRSA SSIs while the full bundle was associated with a significant reduction in S. aureus, MRSA, MSSA and Gram-positive SSIs. I have pasted the table below (click to magnify), but since the full article is open access, you can also read the full article at BMJ.

This meta-analysis guided the implementation of an ongoing trial funded by AHRQ, so more data are coming soon. But what to make of this paper in the context of the recent REDUCE MRSA trial?  I myself am concerned that widespread mupirocin use in all ICU patients will select for resistant S. aureus isolates and render this highly-effective SSI bundle ineffective in short order. It will be sad to watch this example of the 'tragedy of the commons' play out in real time, as I suspect we will. And we will only have ourselves to blame. The data is right before our eyes.

Another Staph aureus vaccine failure

The April 3rd JAMA contains the results of a wonderfully designed and executed study by Fowler and colleagues assessing the benefits of a novel (V710) vaccine targeting S. aureus infection in cardiothoracic surgery. The study was negative (i.e. the vaccine didn't work) and highlights how little we know in 2013 about how humoral immunity works for this important human commensal. But first the study and results...

Among 8031 patients entered into the study, the vaccine was given between 14 and 60 days pre-op to 3981 randomly-selected patients prior to surgery while 3982 received saline placebo. The study was powered to detect a 20% reduction in S. aureus bacteremia or deep surgical site infection through 90-days post-op. Secondary outcomes were any invasive S. aureus infection. Three interim analyses were planned but the data monitoring committee terminated the study after the second interim analysis. Thus, only around ~5100 patients completed the full study with 90-day endpoints. Of note, 67% were male, 24% had diabetes, 18% were S. aureus colonized and 2% were MRSA colonized. Randomization appears excellent.

As I suggested, the results are sobering. The primary outcome (deep SSI or bacteremia) occurred in 2.6% of vaccinated patients and 3.2% of controls, p=0.58. There were more adverse events at 14 days in the vaccinated group (31% vs 22% ) and a greater incidence of multiorgan failure. Depressingly, there was far higher mortality secondary to S. aureus infection in the vaccinated group, 23 vs 4.2 per 100 person-years. The overall comparison between vaccinated and unvaccinated for S. aureus related outcomes is striking and humbling. I've pasted Table 4 from the study below, for your review (click on it to enlarge).

The authors of the study point out that their study isn't the first to find worse outcomes in a vaccinated group and also that MRSA infections were more common in the vaccinated arm of the trial. But I don't buy their suggestion that MRSA was a significant contributor to the poorer S. aureus related outcomes in the vaccinated group. There just wasn't enough MRSA disparity between the vaccinated and control groups. I wonder if part of the answer to higher mortality in the vaccinated group could be explained by this old paper by Heiman Wertheim and colleagues that I discussed several years ago. Wertheim report significantly lower mortality among S. aureus carriers vs. non-carriers. Could the vaccine be upsetting the delicate protective effect of pre-existing S. aureus colonization?

There is an excellent accompanying editorial by Preeti Malani and I urge you to read it. She does a wonderful job putting this study in historical context and pointing a path forward for HAI prevention research. The money quote from her editorial is: "Ultimately, the results of the study by Fowler et al say more about the need to rigorously study infection prevention in general than about S aureus per se." I couldn't agree more.

Image source: Vance Fowler, MD MHS from Duke

Guest Post: A "Hybrid" Surveillance approach for SSI

Dr. Connie Savor Price has been co-project director and PI on a 2009 AHRQ ACTION contract charged with improving the measurement of surgical site infection risk stratification and outcome detection. The final report has just been published online and she was kind enough to stop by our humble blog to briefly describe the project.

With pressure on infection control programs to expand surveillance for public reporting and pay-for -performance, increasing surveillance efficiency without sacrificing data validity creates a conundrum. Purely automated systems for surgical site infection (SSI) surveillance have been developed and utilized, but are not validated or generalizable for these purposes.

In this report, we describe development of "hybrid" surveillance approach using highly sensitive electronic algorithms for detection of SSI targeted for subsequent human-adjudication. Electronic algorithms to detect deep and organ-space SSI after coronary artery bypass grafting, total hip and knee arthroplasties, and herniorrhaphies were created using a sample of nationwide Veterans Affairs Surgical Quality Improvement Program data (VASQIP). The algorithms were tested against VASQIP data, and then assessed for generalization using data from hospitals from three different, external (non-VA) healthcare systems.

Although all algorithms performed reasonably well at identifying deep and organ-space SSI among the VASQIP test data set, performance was variable when tested against data from the outside systems. As one would expect, the observed variation was primarily due to differences in the data collected and stored electronically in each system. While not surprising, perhaps some are disappointed that this research did not produce a universally applicable surveillance tool for "out-of-the-box" utility for all infection control programs. But just wait. As meaningful use incentives help us move toward interoperable electronic health records throughout the United States, this surveillance strategy will hold promise as a reliable tool for detecting potential surgical site infection.

The end of post-op prophylactic antibiotics?

One of the best approaches we have for dealing with in-hospital antimicrobial resistance is stewardship - using antibiotics only when the patient is most likely to benefit. It's been known for a long time that there is little benefit in extending prophylactic antibiotics beyond the end of surgery, yet this practice still persists. Imamura et al. just published an RCT in Lancet ID that examined the possible benefits of extending prophylaxis in patients with gastric cancer undergoing distal gastrectomy for cure.

The trial was an open-label, stratified (by ASA score) randomized trial in seven hospitals. All patients were assigned (1:1) to receive cefazolin 1g before incision and every 3 hours. Those in the extended prophylaxis group received 1g at closure and twice daily for two  postoperative days.  Using CDC definitions, infection control staff monitored for SSI while in hospital and surgeons monitored post-discharge for 30 days.

In the intention-to-treat analysis, 176 patients received standard prophylaxis and 179 received extended prophylaxis.  Randomization appeared adequate with similar operative times and estimated blood loss in each arm; however, 4 patients in the extended prophylaxis arm received transfusions versus none in the standard arm.  I've pasted Table 2 above, so you can see the results broken down into superfical and deep SSI.  Twice as many patients in the extended arm developed an SSI (RR 0.51 95% CI 0.22-1.16), but this was not statistically significant. Caveats: open-label study and SSI not monitored by independent researchers after discharge.

The authors and the accompanying editorial (both behind a paywall) each conclude that extended prophylaxis is not recommended. Although it is likely true, as Hedrick and Sawyer state in their editorial, that "the study is unlikely to have a major impact in the USA and other countries where the maximum duration of perioperative antibiotics is limited to 24 h and is carefully monitored and regulated."

A surgical site infection enhancement bundle?

A new paper in the Archives of Surgery evaluated the implementation of a surgical site infection (SSI) prevention bundle for colon surgery (see free text of the paper here). The bundle contained the following components:

• Omission of mechanical bowel preparation
• Preoperative and intraoperative patient warming
• Increased concentration of inspired oxygen during and immediately after the surgical procedure
• Limiting intraoperative intravenous fluid volumes
• Use of wound barriers to protect the surgical wound from contamination during the procedure 

Each component of the bundle was supported by 1 or more randomized trials demonstrating reduction in SSIs. About 200 patients were randomized to receive either the bundle or standard care. SSIs were determined by IPs using CDC case definitions. The study was terminated after a planned interim analysis revealed a <1% chance of showing a positive effect of the bundle were the study to continue to the accrual goal.

The overall rate of infection was 35%. In the control group, 24% of patients developed an SSI vs. 45% in the intervention group (p .003). In multivariate analysis, the bundle was shown to an independent predictor for SSI (RR 2.49, CI95 1.36-4.56).

I was struck by the very high rate of infection in this study, so I looked at CDC's most recent surveillance report, which shows that the mean pooled infection rates for colon surgery depending on risk category ranges from 3.99% to 9.47%. The authors postulate that their case ascertainment may be greater since the study was performed at a VA hospital where outpatient follow-up of patients is much easier to track. However, even in light of that, the rate still seems quite high. But on the other hand, unless there is something very unique about these patients or the care provided at this hospital, you might think that an effective prevention bundle would have even more impact in a setting with exceedingly high infection rates. This raises more concern that the bundle was not just ineffective but actually increased the risk of post-operative infection.

This paper is another example of how immature implementation science remains. I think the authors of this paper are correct to conclude that bundles of evidence-based interventions need to be formally tested before there is wide spread implementation.

Gentamicin-collagen what?

Am I the only hospital epidemiologist who had absolutely no idea these things existed? Now I’m glad I ignored them for so long, because they don’t seem to work worth a damn, according to studies recently published in JAMA and NEJM. They might even be harmful!

Laziest possible post about the new CMS rule

I am on vacation. Last week I biked across Iowa with 9,999 other people (see photo below), and I’m now in Michigan, recovering from my bike ride across Iowa. So I haven’t done much deep thinking about the new CMS rule related to healthcare associated infections. From what I understand, participation in the Medicare program (at least receipt of full payment) will soon require surveillance and reporting (through NHSN) of CLABSI (beginning in 2011; ICU only) and SSI (beginning in 2012). The rates will eventually be reported via the hospital compare website. This doesn’t mean a lot to hospitals that already perform CLABSI and SSI surveillance, unless they don’t currently report through NHSN, in which case they’ll have to get enrolled.

We’ve already blogged about pitfalls in public reporting, and about problems with the NHSN definitions, validation, etc. So I really don’t have anything new to say about this rule. I refer all interested readers to a six-part series at Safe Healthcare (only 2 posts so far, 4 to come) on the new rule.

Avoiding SSIs

It's not often that a major newspaper prints an editorial on healthcare associated infections, but here's one from this morning's Boston Globe.

Should we just skip SCIP?

There is a new paper and editorial on SCIP (Surgical Care Improvement Project) in this week's JAMA. SCIP is a Medicare project to improve compliance with practices that have been shown to reduce surgical site infections. These metrics include correct antimicrobial selection and timing, and appropriate hair removal. In this study the authors correlate compliance with SCIP metrics to surgical site infection rates, and the conclusion is that SCIP compliance doesn't correlate with reduction in SSIs. However, in my opinion, there's a huge problem with this study. The outcome data on SSIs were obtained using administrative data (ICD-9 codes), which are notoriously inaccurate. Kurt Stevenson showed that the positive predictive value of ICD-9 codes when compared to NHSN surveillance methods for 8 different categories of surgical site infections was as low as 14% and only as high as 51%. Thus, I don't think this study should sway our opinion about SCIP one way or the other. Since nearly all hospitals collect SCIP data and some states mandate NHSN SSI surveillance, the data should be available to replicate the study with better outcomes data. And if that shows similar findings, SCIP should be put to pasture.

Obesity and surgical site infections

Abstracts being presented at a national GI meeting this week demonstrate the impact of obesity on surgical complications. One study found that patients with a waist circumference of 45 inches or more were three times more likely to develop a surgical site infection after rectal cancer surgery. The authors of another study demonstrate increased surgical complications in obese patients and go on to criticize pay-for-performance programs that reward surgeons for better outcomes given that a patient's obesity is out of the surgeon's control. Moreover, they claim that since obesity is more common among minority patients, these policies may have adverse unintended consequences that result in discrimination.

Rhinoceroses and Total Hip Arthroplasty

Distinctions are very important. I was just visiting Ohio last week and had the chance to visit the Columbus Zoo. It's a pretty cool place if you like zoos. I enjoyed reading about various animals and learned that the Black Rhino is endangered, while the White Rhino is not. Thus, it would make sense to spend your conservation money, if you have some, on Black Rhinos first, since time is running out. In infection control, we ought to do the same thing, but in reverse; spending our limited resources on preventing more common infections first. Also, with the rise of public reporting and other methods of interhospital comparison, efforts must be made to place hospitals on a level playing field. There is a nice study that highlights these two issues in the May ICHE by Surbhi Leekha and colleagues at the Mayo Clinic in Rochester, MN.

They examined at a 5-year cohort (2002-2006) of all total hip arthroplasties (primary and revision) and looked to see who developed SSI, using CDC definitions. After controlling for age, gender and NNIS index, patients who had a revision total hip arthroplasty had twice the odds of SSI compared to primary surgery (OR=2.2, 95% CI 1.3-3.7). The difference was even more stark when outcomes were restricted to deep or organ space SSI with revisional surgery associated with four times the odds of SSI (OR 3.9, 95% CI, 2-7.9). One note, they didn't appear to control for duration of surgery as a confounder, even though it was associated with both revisions and SSI. I think this is correct. They were not completing a risk-factor study, but were interested in outcomes.

The usual caveats apply to these types of studies including a single center study and a relatively unique single center at that. However, this is an important study and if these findings hold up at other institutions, which they most certainly will, this suggests that the case-mix of revision and primary hip arthroplasty must be taken into account when SSI rates are reported and hospitals compared. Perhaps an easier solution, as the authors suggest, is to treat them as two different animals, if you will, and report them separately. Also, if one wanted to target specific infections or high-risk procedures, these results suggest targeting revision surgeries over primary ones.

Note: Surbhi is joining the group at my old Maryland stomping grounds and I know everyone is excited for her to arrive.

Everybody loves chlorhexidine!

There are two randomized controlled trials* about surgical site infection (SSI) prevention published in the New England Journal of Medicine this week. In one multicenter study, investigators randomized 849 patients undergoing clean-contaminated surgery to preoperative skin preparation with chlorhexidine (CHG)-alcohol or povodone-iodine (P-I), using a primary outcome of SSI at 30 days postoperatively. By intent-to-treat analysis, CHG-alcohol use resulted in lower overall SSI rates (9.5% vs. 16.1% for P-I; p=0.004), and lower rates of superficial (4.2% vs. 8.6%) and deep (1% vs. 3%) incisional SSI.

So CHG, which is already preferred for skin prep prior to intravascular catheter placement, and which is being used increasingly to bathe ICU patients, in catheter dressings, and in oral care, should probably also be preferred for preoperative skin prep. CHG for everyone, everywhere!

In a second multicenter study, Dutch investigators screened 6771 newly admitted patients for S. aureus nasal carriage, using real-time PCR. Of the 1251 S. aureus carriers, 918 were randomized to receive 5 days of either nasal mupirocin (2% ointment twice daily) and CHG soap (daily), or placebo. The rate of healthcare-associated S. aureus infections was almost 60% lower in the mupirocin-CHG group (3.4%, versus 7.7% for placebo; relative risk 0.42 [0.23-0.75]. Most enrolled patients were surgical (88%), and most S. aureus infections were SSI (82%). Among surgical patients, the rate of deep SSI was lower in the mupirocin-CHG group (0.9 vs. 4.4%; RR 0.2 [0.07-0.62]).

The implications of this study are less clear, since the relative importance of the two topical therapies (nasal mupirocin and CHG soap) is unknown. Many centers now routinely use pre-operative CHG bathing for elective procedures. Until we know whether screening and targeted decolonization is superior to the preoperative bathing of all patients with CHG soap, this approach should be reserved for high risk procedures (e.g. cardiac surgery, orthopedic implants).

Dick Wenzel wrote a nice editorial about both pieces, and uses the opportunity to make a point we’ve made several times before in this blog: interventions that can be applied to all patients and that reduce all infections are preferred to organism-specific approaches that carry the added expense and logistical difficulty associated with identifying all carriers of an organism.

*COI alert: Both studies were industry supported—one by Cardinal Health, and one by grants from GlaxoSmithKline, Roche, bioMerieux, and 3M.