Any surgery carries with it some degree of risk, and a significant one is the risk of developing an infection at an incision site. In Canada, it’s estimated that more than six per cent of surgical incisions become infected, which can lead to complications, delay in recovery, more time spent in hospital, and increased health care costs.
The sutures used during surgery have long been thought to be a key contributor to surgical site infections (SSIs). Bacteria can adhere to the sutures, where it can multiply and be transferred into the wound. Antimicrobial sutures ― sutures coated with an antibacterial agent ― were developed to reduce the incidence of SSIs. Those currently available in Canada are coated with triclosan.
CADTH — an independent agency that assesses health technologies ― finds and summarizes the research on drugs, medical devices, and procedures. CADTH’s Rapid Response service provides summaries and critical appraisal of the evidence in as little as 30 days and had recently been asked to update a previous CADTH review of the evidence on antimicrobial sutures for the prevention of SSIs.
Whereas the earlier CADTH review didn’t find enough evidence to conclude that antimicrobial sutures reduce the risk of SSIs, the update found some new evidence suggesting that they might — by about 30% compared with conventional, non-coated sutures. The benefit shown in the new studies was specifically in patients undergoing abdominal surgery, colorectal surgery, and the closure of leg wounds — surgeries where infection is more likely. Antimicrobial sutures were not shown to reduce SSI risk for surgeries with a lower risk of infection ― such as breast or cardiac surgeries — or for surgical sites that are already contaminated or dirty. However, the new evidence has a number of limitations.
If antimicrobial sutures do reduce the incidence of SSIs compared with less expensive conventional sutures, are they worth the extra cost? The answer is, we’re not sure. The available cost-effectiveness information is from a non-Canadian context, so whether the money saved by averting the added health care costs associated with SSIs would offset the higher cost of antimicrobial sutures is unclear. In addition, the risk of adverse events with antimicrobial sutures, including the development of drug-resistant bacteria, is not known.
Many other strategies are used to prevent SSIs, with proper hand hygiene being the most effective and least expensive. A CADTH review found that the current, evidence-based hand hygiene guidelines include removing artificial nails and jewellery then washing visibly soiled hands with plain soap and water prior to hand antisepsis, using an antisepsis product that is both effective at killing organisms and at preventing their regrowth for an extended period of time, and ensuring the product is applied to the hands for the length of time recommended by the manufacturer.
Another long-standing practice to reduce SSIs is for surgical staff to wear masks in the operating room. According to a CADTH review on this topic, although there have been few studies to measure the effectiveness of wearing masks, clinical practice guidelines based on expert opinion are consistent in recommending their use.
The use of preoperative skin antiseptic products to prepare a patient’s skin at the surgical site is another well-established way of preventing SSIs. CADTH conducted a systematic review of the three main types of topical antiseptics — chlorhexidine, povidone-iodine, and alcohol — to see if they reduced SSIs and the available evidence on their effectiveness was inconclusive. However, it was clear that these products are effective at reducing the number of microorganisms living on the skin that could infect a surgical incision.
For patients at high risk of infection or for whom an infection would have grave consequences, prophylactic antibiotics are often administered before surgery, and their efficacy in preventing SSIs in these patients is well established. Prophylactic antibiotics are most effective when given one to two hours before surgery, but this time frame can be hard to accommodate. A CADTH review of the evidence concluded that prophylactic antibiotics might also be effective when given 30 to 60 minutes before surgery; however, better-designed trials are needed to confirm this finding.
The prevention of surgical site infection has become a topic of increased interest over recent years, and CADTH has produced several reports on this subject. Those mentioned in this article and many more can be accessed free of charge on the CADTH website: www.cadth.ca/RapidResponse.