Background: In the worldwide, real-life setting, some candidates for right colectomy still receive no bowel preparation, some receive oral antibiotics alone, some receive mechanical bowel preparation alone, and some receive mechanical bowel preparation with oral antibiotics, with varying degrees of compliance to preoperative intravenous antibiotic prophylaxis. Previous studies mainly focused on left-sided colorectal anastomoses while less attention has been devoted to right-sided ileocolic anastomoses. When high-level evidence from randomized clinical trials is lacking, multiple-treatment propensity score weighting analysis of prospective data on the basis of generalized boosted model is superior to a simple propensity score-matching analysis and to an inverse probability weighting in terms of external validity and bias reduction. Methods: This is an analysis on the basis of machine-learning procedures of 2,617 patients who underwent elective right colectomies. Results: The risk of surgical-site infections (5.0% after no bowel preparation) was significantly lower after mechanical bowel preparation with oral antibiotics (4.0%, P = .017), significantly greater after mechanical bowel preparation alone (8.6%, P = .019), and comparable after oral antibiotics alone (3.9%). The risk of anastomotic leakage (3.2% after no bowel preparation) was significantly greater after oral antibiotics alone (4.8%, P = .013). Concerning secondary outcomes, no significant differences were recorded for the risk of overall morbidity and reoperation. The risk of readmission (3.0% after no bowel preparation) was significantly reduced after mechanical bowel preparation with oral antibiotics (1.5%, P = .046), and the risk of major morbidity (5.1% after no bowel preparation) was significantly greater after oral antibiotics alone (6.7%, P = .007). Conclusion: This multitreatment machine-learning analysis, despite some limitations, showed that mechanical bowel preparation with oral antibiotics is associated with a decrease in surgical-site infections after elective right colectomy compared with no bowel preparation.
