LAUSR

Objectives This randomized, single-center, retrospective, comparative cohort study is aimed at investigating the optimal time interval from self-expandable metal stent (SEMS) placement to surgery and potential risk factors for complications in patients with acute malignant colorectal obstruction. Methods A total of 64 patients with left-sided acute malignant colorectal obstruction treated with SEMS placement and subsequent surgery between January 2013 and September 2020 were enrolled and allocated to a case group (SEMS placing time ≤ 14 days; n = 19 patients) and a control group (SEMS placing time > 14 days; n = 45 patients). The primary outcome was the difference in baseline information, patients' conditions during surgery, and postoperative conditions between the two groups. The secondary outcome included potential risk factors of postoperative complications. The propensity score matching (PSM) and super learner (SL) methods were used to eliminate multiple confounding factors of baseline data. A cohort of 21 samples was used for external validation, comprising 6 cases and 15 controls. Results A significant difference was observed between the two groups in intraoperative blood loss (P = 0.009), postoperative hospital stay (P = 0.002), postoperative complications (Clavien-Dindo grading ≥ II) (P < 0.001), stoma creation (P < 0.001), and primary anastomosis (P < 0.001). After a 1 : 3 PSM analysis, no statistically significant differences between eight confounding variables of the two groups were observed (P > 0.05). Caliper set as 0.2 multiple logistic regression analysis showed that the potential risk factor for postoperative complications was SEMS placing time (RR = 0.109, 95% confidence interval (CI) = 0.028-0.433; P = 0.002), indicating that SEMS placing time > 14 days was an independent risk factor for postoperative complications in bridge-to-surgery (BTS) setting. The area under the AUC curve was 76.7% and validated using the validation cohort. Conclusions Long duration of SEMS placement (>14 days) may not influence surgical difficulty but could increase the risk of postoperative complications.