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New standard of care in SSI prevention
Move to chlorhexidine-alcohol patient prep expected
The clear conclusion of a recently published study is preoperative cleansing of the patient's skin with chlorhexidine-alcohol is hands-down better to cleansing with povidone-iodine for preventing surgical-site infection after clean-contaminated surgery.1 Now it gets interesting.
For starters, povidone iodine is used as the skin prep in almost three-quarters of all surgeries, with chlorhexidine alcohol the choice for only about 10% of operations to cleanse patient skin. Costs — for the solutions and materials, not for the later surgical-site infections (SSIs) — are a clear factor in that unbalanced proportion. However, the nature of the clinical trial means the results can be widely extrapolated to other settings, says lead author Rabih O. Darouiche, MD, lead author and director of the Center for Prostheses Infection, Baylor College of Medicine in Houston. In short, it's a game changer.
"Overall, we saw a 41% reduction" in SSIs, he reports. "I cannot think of any confounding variable that essentially would change the potential efficacy of a certain antiseptic preparation in one city vs. another or one hospital vs. another. This is a really easy — a practical, quick, and very powerful approach. I really see no barriers that could limit the implementation of this approach on a national basis."
Since 2002, the Centers for Disease Control and Prevention has recommended chlorhexidine-alcohol for skin cleansing of the insertion site for vascular catheters. However, the CDC has not issued a similar recommendation for skin cleansing at surgical sites, citing a lack of clinical evidence. Until now. Published in The New England Journal of Medicine, Darouiche's study is expected to lead to new CDC recommendations for surgical-site prep to prevent endogenous infections from patient flora.
Talking to AHC Media, publisher of Same-Day Surgery, the day the clinical trial results were published, Darouiche observed, "Many experts of the field think these results should be able to switch the standard of care from povidone-iodine to chlorhexidine-alcohol for preoperative skin cleaning."
One of them is veteran health care epidemiologist Richard Wenzel, MD, professor and chairman of the department of internal medicine at the Medical College of Virginia in Richmond, who wrote an accompanying editorial on the study.2
"The switch to a different skin prep would be at some additional cost, but it is very small compared with preventing 40% of surgical-site infections," Wenzel tells AHC Media. "And this is not an extra procedure. There is no opportunity costs in other words for the surgeon, he or she is already going to do a prep, and they are just changing the materials. It's absolutely remarkable."
Breaking down the cost factors
The cost of the applicator that contains the chlorhexidine and alcohol is about $6 — roughly twice as much as the iodophor product, Darouiche explained.
"On average, we applied two applicators that contained chlorhexidine-alcohol on the skin of an individual patient in the study, so for each patient who received chlorhexidine-alcohol an additional cost of $9 was incurred," he adds. "This study showed that you would have to apply chlorhexidine-alcohol rather that povidone-iodine in 17 patients in order to prevent one case of surgical-site infection. So, 17 patients times $9 is $153. That pales in comparison to how much money you can save by preventing the onset of surgical-site infection, which we know can cost anywhere from a few thousands of dollars to tens of thousands of dollars."
The Darouiche clinical trial randomly assigned adults undergoing clean-contaminated surgery in six hospitals to preoperative skin preparation with chlorhexidine-alcohol scrub or povidone-iodine scrub and paint. Enrolled patients were randomly assigned in a 1:1 ratio to have the skin at the surgical site preoperatively scrubbed with an applicator that contained 2% chlorhexidine gluconate and 70% isopropyl alcohol or preoperatively scrubbed and then painted with an aqueous solution of 10% povidone-iodine. The primary outcome was any surgical-site infection within 30 days after surgery.
A total of 849 subjects (409 in the chlorhexidine-alcohol group and 440 in the povidone-iodine group) qualified for the intention-to-treat analysis. The overall rate of surgical-site infection was significantly lower in the chlorhexidine-alcohol group than in the povidone-iodine group (9.5% vs. 16.1%). Chlorhexidine-alcohol was significantly more protective than povidone-iodine against both superficial incisional infections (4.2% vs. 8.6%) and deep incisional infections (1% vs. 3%) — but not against organ-space infections (4.4% vs. 4.5%).
"Actually we never anticipated that this would reduce the rate of organ-space infection," Darouiche explains. "Most incision infections are caused by organisms that reside on the patient's skin. That's why we anticipated that the chlorhexidine alcohol would significantly reduce the rate of incisional infections, but the skin antiseptics are not expected to find the way below the incisional area and prevent infection in deep organs and spaces."
Moreover, efficacy of infection prevention was not dependent on the organism, meaning MRSA, and all its attendant costs, is as likely to die on the patient's skin as any other bug. Culture of the surgical site in 60 of 61 infected patients yielded growth of organisms (a total of 107 isolates) and similar proportions of infected patients in the two study groups. Gram-positive aerobic bacteria (63 isolates) outnumbered gram-negative aerobic bacteria (25 isolates) by a factor of 2.5, with 38% of cultures polymicrobial.
"The protection by chlorhexidine-alcohol was essentially the same across different groups of organisms," Darouiche emphasizes.
The 41% reduction in SSI risk is comparable to a 49% reduction in the risk of vascular catheter-related bloodstream infection in a meta-analysis that showed the superiority of skin disinfection with chlorhexidine-based solutions vs. 10% povidone-iodine.3 Although both the antiseptic preparations studied possess broad-spectrum antimicrobial activity, the superior clinical protection provided by chlorhexidine-alcohol is probably related to its more rapid action, persistent activity despite exposure to bodily fluids, and residual effect, Darouiche hypothesizes. As a result, some infections that might have been seeded from the patients' flora during the procedure are prevented. Since two-thirds of surgical-site infections are confined to the incision, optimizing skin antisepsis before surgery could result in a significant clinical benefit and immense cost savings, he emphasizes.
"Personally, I think better patient care is the primary outcome, and everything else is secondary to that," Darouiche says.