Cost-minimization analysis of postoperative antibiotic use in high horseshoe anal fistula: evidence from a randomized...

To evaluate the total societal costs of postoperative antibiotic use compared to non-use in patients undergoing surgery for high horseshoe anal fistula (HHAF), based on a randomized controlled trial.

We conducted a single-blinded randomized controlled trial in 90 patients with HHAF treated using a standardized loose combined cutting seton (LCCS) procedure at the Department of Colorectal Surgery, China-Japan Friendship Hospital, between January and October 2023. Participants were randomly assigned to either a postoperative Antibiotic group or a No Antibiotic groups. The primary outcome was total societal cost. Clinical outcomes, including wound healing time and early recurrence, were assessed as secondary measures A societal cost-minimization analysis (CMA) was performed, encompassing direct medical costs, outpatient visit costs, and indirect costs due to lost productivity. Patient follow-up was completed by December 2024.

Ninety patients were randomized equally (45 per group) with comparable baseline data. The Antibiotic group showed significantly higher hospitalization costs (¥13,202 ± 3,054 vs. ¥9,322 ± 1,205; p < 0.001) and longer stays (12.5 ± 5.8 vs. 7.9 ± 2.4 days; p < 0.001), without differences in wound healing (p = 0.490). Regression confirmed that both incision number (β = 1735.18, p = 0.020) and antibiotic use (β = 3287.06, p < 0.001) independently increased cost, with a significant interaction (β = 3641.00, p = 0.010). Antibiotic use also led to more outpatient visits (5.25 vs. 2.75; p = 0.013) and higher total societal costs (¥9,802 vs. ¥7,931; p = 0.014). Sensitivity analyses under multiple scenarios consistently confirmed higher overall costs in the Antibiotic group.

Routine postoperative antibiotics showed no significant additional clinical benefit in terms of wound healing or recurrence in HHAF patients treated with LCCS, yet significantly increase societal costs and postoperative burdens. A selective, evidence-based approach to antibiotic use should be adopted in the surgical management of complex anal fistulas.

This study was retrospectively registered in the Chinese Clinical Trial Registry (ChiCTR2400093477) on December 5, 2024, after the enrollment of participants began in January 2023. The retrospective registration is in accordance with the journal's editorial policy for studies involving healthcare interventions in human participants.