BACKGROUND: Surgical site infection remains a common complication after colectomy. Mechanical bowel preparation and oral antibiotics are used to reduce infectious morbidity, but whether their benefit varies across body mass index is unclear. OBJECTIVE: To evaluate the association between preoperative bowel preparation regimen and 30-day postoperative outcomes after elective colectomy for non-metastatic colon cancer, and to assess whether these associations vary across body mass index. DESIGN: Retrospective cohort study. SETTINGS: American College of Surgeons National Surgical Quality Improvement Program targeted colectomy database, 2015-2023. PATIENTS: Adults undergoing elective colectomy for non-metastatic colon cancer (N = 97,395). MAIN OUTCOME MEASURES: Thirty-day surgical site infection, anastomotic leak, and overall postoperative complication. RESULTS: In unadjusted analyses, surgical site infection occurred in 8.7% of patients with no bowel preparation and 5.0% with combined mechanical plus oral antibiotic bowel preparation. In adjusted modified Poisson models, all bowel preparation regimens were associated with lower risk of 30-day postoperative complications versus no preparation (all p < 0.001), with the lowest adjusted relative risk for combined preparation (any surgical site infection: 0.60; anastomotic leak 0.66; any complication: 0.70). In stratified analyses, combined preparation and oral antibiotics alone were superior to no preparation for both left- and right-sided resections, but mechanical preparation alone was not superior to no preparation for right-sided resections. Evidence of effect modification by body mass index was limited (interaction p = 0.09 for surgical site infection, p = 0.26 for overall complications), including when stratified by resection site. LIMITATIONS: Observational design with potential residual confounding; registry data lacked preparation adherence/quality and granular institutional prevention practices; estimates were less precise at extreme body mass index values. CONCLUSIONS: Bowel preparation regimens containing oral antibiotics were associated with lower 30-day surgical site infection and complication risk across the body mass index continuum. These findings suggest that the effectiveness of oral antibiotic-containing bowel preparation is preserved across BMI levels. See Video Abstract.
Wu et al. (Mon,) studied this question.