Aqueous vs Alcoholic Antisepsis with Chlorhexidine for skin Excisions - The AVALANCHE trial.

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Preoperative cleansing of the skin with antiseptic preparations at the site of surgical excisions (preoperative skin antisepsis) is common practice before every surgery worldwide, and aims to reduce surgical site infection. However, in most contexts, no definitive scientific consensus exists regarding which preoperative skin antiseptic preparations are most effective. This randomised controlled trial aims to close an existing gap in the evidence base surrounding optimal preoperative skin antisepsis before clean surgery - a practice most general practitioners carry out several times per week when they perform skin excisions. It is currently suspected on the basis of incomplete and methodologically inconsistent evidence that alcoholic antiseptic preparations are likely to be more effective than aqueous preparations for the prevention of surgical site infection (SSI) after clean surgery. This study aims to find definitive proof for this theory by determining whether there is a difference in the incidence of SSI after minor skin excisions in general practice when alcoholic chlorhexidine is used for preoperative skin antisepsis by comparison to when aqueous chlorhexidine is used. It is hypothesised that use of alcoholic chlorhexidine will reduce SSI by comparison to aqueous chlorhexidine. To implement this study, multiple general practices in the Mackay region which perform large numbers of skin excisions each year will be recruited. Consecutive patients over the age of 18 presenting to participating practices will be asked to participate in the trial and those that agree to partake will be randomised by a computer-generated random number table to receive preoperative skin antisepsis with either 0.5% chlorhexidine dissolved in 70% alcohol or 0.5% chlorhexidine dissolved in water. All other techniques and materials used for both preoperative skin antisepsis and the skin excision itself, as well as all aspects of post-operative care, will be kept constant between the two groups, and will align with a pre-specified surgical and wound protocol. Following their excision, patients will be assessed for the presence or absence of SSI by their treating doctor or nurse when they present for removal of sutures, or at any other time if they re-present due to suspicion of SSI or for any other reason. Rates of SSI will then be recorded, calculated and compared between the two groups using the statistical analysis software SPSS to determine if there is a significant difference in effectiveness between aqueous and alcoholic chlorhexidine. Hopefully the results of this study will help to provide direction to doctors regularly carrying out clean surgery, who at present have little definitive evidence to guide their choice of preoperative skin antiseptic preparations. Looking further, if a difference is found between aqueous and alcoholic chlorhexidine, we would aim for this research to impact current guidelines on preoperative skin antisepsis and evoke behaviour change from doctors and nurses which leads to a reduction in SSI rates in general practice.