Risk Stratification for Organ/Space Surgical Site Infection in Digestive System Cancer: A Prospective Cohort Study

Background: Organ/space surgical site infection (organ/space SSI) is one of the serious postoperative complications, closely related to a poor prognosis. Few studies have attempted to design risk scoring systems for patients with digestive system cancer. This study aimed to develop a simple and practical risk stratification score for these patients to identify a priori risk of organ/space SSI.Methods: This prospective cohort study was based on two prospective studies (NCT02756910, ChiCTR-IPR-17011099), including patients undergoing elective radical resection of digestive system cancer. Logistic regression analysis was used to identify the determinant variables. The incidence of organ/space SSI stratified over perioperative factors was compared and compounded in a risk score.Results: Among the 839 patients, 51 developed organ/space SSI (6.1%) within 30 days after surgery. Patients undergoing gastrectomy (OR=8.466, 95% CI: 2.728-26.270, P<0.001), colorectal resection (OR=11.180, 95% CI: 3.921-31.881, P<0.001) and pancreatoduodenectomy (OR=9.054, 95% CI: 3.329-24.624, P<0.001) with an anaesthesia time > 4 h (OR=2.335, 95% CI: 1.035-5.271, P=0.041) and prolonged intensive care unit (ICU) stays > 24 h (OR=4.243, 95% CI: 1.715-10.498, P=0.002) had a significantly higher risk of organ/space SSI. These risk factors (procedure type, anaesthesia time, prolonged ICU stays) were also associated with an increase in organ/space SSI rates based on a compounded score (P<0.001). Comparisons with the overall population revealed that patients with 0 or 1 risk factor (n=602) had an organ/space SSI rate of 2.8% (RR=0.197, 95% CI: 0.112-0.345), those with 2 risk factors (n=223) had an organ/space SSI rate of 13.0% (RR=3.641; 95% CI: 2.138-6.202), and those with 3 risk factors (n=14) had an organ/space SSI rate of 35.7% (RR=6.405, 95% CI: 3.005-13.653).Conclusion: The risk stratification score in this study provides a simple and practical tool to stratify patients with digestive system cancer so that the relative risk of developing postoperative organ/space SSIs can be predicted.Trial Registration: This study was based on one randomized controlled trial (NCT02756910) registered at ClinicalTrials.gov on April 29, 2016 and one prospective cohort study (ChiCTR-IPR-17011099) registered at the Chinese Clinical Trial Registry on April 9, 2017.