Extended Post-Operative Antibiotic Usage Does Not Reduce Surgical Site Infections after Spinal Surgery

Background: Currently there is not a clear basis of evidence for post-operative antibiotic duration in spine surgery. A better understanding of risk factors and proper dosing for antibiotics will help improve outcomes and further define appropriate antibiotic use. Patients and Methods: A single-center retrospective cohort study of all patients undergoing spinal fusions and/or decompressions between January 1, 2018, and July 1, 2023 was performed. Patient demographic data and surgical information were collected. The exposure variable assessed was the duration of post-operative antibiotic administration. The primary outcome was incidence of surgical site infections (SSI). Uni-variable and multi-variable analysis were used to determine risk factors for infection. Results: A total of 5,656 procedures were performed by 25 different orthopedic spine- or neurosurgery-trained surgeons. The incidence of SSI was similar between the <= 24 h of antibiotic group and the >24 h antibiotic group, 0.50% and 0.45%, respectively (p = 0.769). In multi-variable analysis, only a body mass index (BMI) over 30 was associated with increased risk for SSI (odds ratio 2.54 [1.12, 5.74]). Conclusion: We observed no significant difference in the incidence of SSI among patients who were administered <= 24 h of post-operative antibiotics compared with those who we administered >24 h post-operative antibiotics. A BMI >= 30 was a risk factor for SSI in both uni-variable and multi-variable analysis.