Risk Stratification for Superficial Surgical Site Infection after Emergency Trauma Laparotomy.

Background: Superficial surgical site infections (S-SSIs) are common after trauma laparotomy, leading to morbidity, increased costs, and prolonged length of stay (LOS). Opportunities to mitigate S-SSI risks are limited to the intra-operative and post-operative periods. Accurate S-SSI risk stratification is paramount at the time of operation to inform immediate management. We aimed to develop a risk calculator to aid in surgical decision-making at the time of emergency laparotomy. Methods: A retrospective cohort study of patients requiring emergency trauma laparotomy between 2011 and 2017 at a single, level 1 trauma center was performed. Operative factors, skin management strategy, and outcomes were determined by chart review. Bayesian multilevel logistic regression was utilized to create a risk calculator with variables available upon closure of the laparotomy. Models were validated on a 30% test cohort and discrimination reported as an area under the receiver operating characteristics curve (AUROC). Results: Of 1,322 patients, the majority were male (77%) with median age of 33 years, injured by blunt mechanism (54%), and median injury severity score of 19. Eighty-eight (7%) patients developed an S-SSI. Patients who developed S-SSI had higher final lactate, blood loss, transfusion requirements, and wound classification. Patients with S-SSI more frequently had mesenteric or large bowel injury than those without S-SSI. Superficial SSI was associated with increased complications and prolonged length of stay (LOS). The S-SSI predictive model demonstrated moderate discrimination with an AUROC of 0.69 (95% confidence interval [CI], 0.56-0.81). Parameters contributing the most to the model were damage control laparotomy, full-thickness large bowel injury, and large bowel resection. Conclusion: A predictive model for S-SSI was built using factors available to the surgeon upon index emergency trauma laparotomy closure. This calculator may be used to standardize intra- and post-operative care and to identify high-risk patients in whom to test novel preventative strategies and improve overall outcomes for patients requiring emergency trauma laparotomy.