APOS-antibiotic prophylaxis for preventing infectious complications in orthognathic surgery: study protocol for a phase III, multicentre, randomised, controlled, double blinded, clinical trial with two parallel study arms.

Background: It is a constant debate among surgeons whether the use of prolonged postoperative antibiotics may reduce surgical site infection rates. As specific treatment guidelines are still lacking, many surgeons continue to use broad-spectrum antibiotics, causing not only increased costs but also contributing to the potential for antibiotic resistance. Hence, there is an urgent need for an appropriately designed prospective clinical trial, to investigate whether a prophylactic use of antibiotics after surgery actually decreases surgical site infections to a clinically relevant degree.

Methods: This study presents a multicentre, randomised, controlled, double-blinded, clinical trial with two parallel study arms to demonstrate that no postoperative antibiotic prophylaxis (AP) is not inferior to antibiotic prophylaxis with respect to surgical site infections in patients having undergone orthognathic surgery. The primary efficacy endpoint is defined as the occurrence of postoperative surgical site infections within 30 days of surgery. Secondary endpoints are further efficacy and subject-oriented parameters within 90 days after surgery. The entire trial is planned for 54 months, with an enrolment of 1420 patients over 39 months by 14 national participating centres.

Discussion: As a highly standardised procedure on an exceeding, healthy and young homogenous study population and identical processes all over the world, elective orthognathic surgery as clean-contaminated procedure provides comparable intervention groups with balanced baseline characteristics, comparable surgical duration, even when performed within multiple centres. Therefore, evaluating antibiotic prophylaxis after orthognathic surgery will be of high scientific value representable for other surgical procedures.

Trial Registration: DRKS-German Clinical Trials Register- DRKS00022838 ; EudraCT No. 2020-001397-30. Registered on 29 March 2021.