Risk factors analysis for surgical site infection following elective colorectal resection: a retrospective regression analysis

Background: A surgical site infection (SSI) is a major post-operative complication from elective colorectal surgery; however, few studies have focused on evaluating the risk factors for SSI. This study aimed to analyze the relative correlation of medical and environmental factors as well as patient-related factors that contribute to the incidence of all types of SSI. Methods: A retrospective search for eligible patients was conducted using the patient database of the Gastrointestinal Surgery Center of the Third Affiliated Hospital of Sun Yat-sen University from January 2011 to August 2017. Pre-operative demographic and surgical data were extracted and recoded according to the study protocol. Univariate and multivariate analyses were performed to clarify factors affecting the incidence of SSI. Propensity analysis was conducted to minimize bias in the demographic characteristics to explore the prophylactic effect of pre-operative administration of oral antibiotics. Results: Univariate analysis of the baseline characteristics revealed that younger age (odds ratio [OR]: 0.378; 95% confidence interval [CI]: 0.218-0.657) and pre-operative oral antibiotic use (OR: 0.465; 95% CI: 0.255-0.850) were protective factors, while pre-operative anemia (OR: 4.591; 95% CI: 2.567-8.211), neoadjuvant chemotherapy history (OR: 2.398; 95% CI: 1.094-5.256), and longer surgical duration (OR: 2.393; 95% CI: 1.349-4.246; P = 0.002) were identified as risk factors for SSI. Multivariate analysis indicated that age (P = 0.003), surgical duration (P = 0.001), and pre-operative oral antibiotic use (P < 0.001) were independent factors that affect the incidence of SSI. Furthermore, a propensity-matched analysis confirmed the protective effect of oral antibiotic use, with a 1-day course of oral antibiotic producing a similar effect to a 3-day course. Conclusions: Age, surgical duration, and pre-operative oral antibiotic use were associated with the incidence of SSI. However, pre-operative oral antibiotic use was the only controllable factor. From the results of our study, pre-operative oral antibiotic use is recommended before elective colorectal surgery and a 1-day course is enough to provide the protective effect.