Link between postoperative ileus and anastomotic leakage: A structural equation modelling approach

Introduction: Postoperative ileus(POI) and anastomotic leakage(AL) are highly associated but the direction of this link is unknown. Indeed, it has traditionally been stated that AL leads to POI(secondary POI). The objective was to statistically determine the best model of link between POI and AL by comparing different Structural Equation Models(SEM). Methods: This is a retrospective analysis of a prospective multicentric database from the Francophone Group for Enhanced Recovery after surgery(GRACE) including patients undergoing colorectal resection or Hartmann reversal between 2014 and 2017. The main outcome measure was the occurrence of postoperative ileus defined by the absence of Gastrointestinal (GI)-3 recovery in or after postoperative day 4 and the occurrence of AL. Results: Among the 2227 patients included, 223 patients experienced POI (10 %) and 72 patients experienced anastomotic leakage (3.2 %). In all the models, POI was significantly increased in case of male gender, older age, opioids consumption, right colectomy, chronic obstructive bronchopneumopathy disease and performance of a stoma, and reduced by Enhanced Recovery Programs (ERP) compliance ≥ 70 % and intake of Non-Steroidal Anti-Inflammatory Drugs. Open surgery was not significantly associated with POI in all the models. In contrast, the male gender was the only factor increasing AL in the model drawn with ERP risk factors for AL. In all the models, POI was highly associated with AL and statistical analyses advocate for POI leading to AL. Conclusion: The findings of the present large study suggest that the more statistically probable model is the one in which POI come first before AL.