Alcoholic vs. aqueous chlorhexidine for abdominal surgery skin preparation: a randomized controlled trial.

Surgical site infections (SSIs) significantly affect patient outcomes and healthcare costs. Alcohol-based chlorhexidine gluconate (CHG) is widely used for preoperative skin preparation; however, aqueous CHG is being considered as a safer alternative in certain settings. This study was designed as an equivalence randomized controlled trial to compare aqueous versus alcoholic CHG for surgical site infection (SSI) prevention in major abdominal operations. A single-centre, randomised controlled equivalence trial (Thai Clinical Trials Registry No. TCTR20211028001, Date October 28, 2021) enrolled 1,326 patients undergoing elective or emergency abdominal surgeries. Participants were randomised to receive skin preparation with either 2% aqueous CHG or 2% alcohol-based CHG. The primary outcome was 30-day total SSI incidence. Secondary outcomes included seroma, wound dehiscence, and hospital stay. Analyses were conducted using intention-to-treat, per-protocol, and as-treated approaches. In the modified intention-to-treat population, total SSI rates were 8.45% (95% CI: 6.44-10.83) in the aqueous CHG group and 10.26% (95% CI: 8.05-12.82) in the alcohol-based group. There was no significant difference in total SSI rates between groups (RD -0.7%, 95% CI: -3.3 to 1.8). Similar results were found in other analyses. Secondary outcomes showed no significant group differences. All findings were within the predefined equivalence margin. Although SSI rates were similar, statistical equivalence was not demonstrated due to wide confidence intervals. Aqueous CHG may still be a suitable alternative where alcohol-based CHG is contraindicated.