Antibiotics and Surgical Site Infection in Expander-Based Breast Reconstruction Trial (ASSERT)

The use of prophylactic antibiotics following postmastectomy tissue expander breast reconstruction (TE-BR) varies widely. The Centers for Disease Control and Prevention (CDC) recommends a single preoperative antibiotic dose for clean and clean-contaminated procedures. This multi-institutional, prospective, randomized controlled trial (RCT) examined whether the CDC-recommended single preoperative dose (SPD) of antibiotics is not inferior to an additional week of postoperative (WPO) prophylactic antibiotics in preventing surgical site infection (SSI) in immediate TE-BR following mastectomy.

Women aged ≥ 18 years undergoing immediate TE-BR were randomized to SPD or WPO groups. The primary outcome was SSI by CDC guidelines within 30 days of surgery. The study used a noninferiority trial design to examine whether the test product (single preoperative dose (SPD)) was not worse than the comparator (1 week of postoperative (WPO) prophylactic antibiotics) by more than a set noninferiority margin of 6%.

In total, five participating centers screened 499 women; 235 were enrolled. A total of 102 patients were randomized to the SPD arm and 112 to the WPO arm, with 21 patients withdrawn. The SSI rate in the SPD arm was 17% as compared with 11% in WPO arm, which is within the noninferiority margin set for this study but not significantly noninferior (p = 0.496). The rate of unplanned TE removal for infection, hospitalization rate, and return to OR rate within 30 days of surgery were comparable between the two groups.

This multi-institutional RCT did not definitively demonstrate that a single preoperative dose of antibiotics is not inferior to a 7-day postoperative antibiotic regimen in preventing SSI in immediate TE-BR; there was also no evidence to support that the 7-day regimen was significantly better. As this represents one of the largest multi-institutional study of its kind, these results have practice-management considerations.