Risk Factors for Surgical Site Infection Following Colorectal Surgery

Background: Surgical site infection (SSI) following colorectal surgery is one of the healthcare associated infection measures used for public reporting and hospital reimbursement. Colorectal SSI risk factors identified by National Health and Safety Network (NHSN) include American Society of Anesthesiologists score, surgical wound class, procedure duration, age, body mass index (BMI), diabetes, type of anesthesia, use of endoscope, facility bed size, and medical school affiliation. While useful for SSI risk stratification, these do not provide full insight into targets for prevention. The objective of this study was to identify additional procedure-specific factors for SSI following colorectal surgery.

Methods: All patients ≥18 years old undergoing colorectal procedures at the University of Maryland Medical Center –in 2015 were included in this analysis. Cases of SSI were identified by infection preventionists using NHSN criteria during routine surveillance. Bivariate and multivariable logistic regression analyses were performed to identify risk factors for SSI in these patients.

Results: Of the 434 colorectal procedures, 39 resulted in an SSI (8.9%). The average patient age was 53.4 years (±17) and the mean BMI was 30.5 (±11). Of the NHSN identified risk factors, age, BMI, and duration of surgery were significant risk factors, while use of endoscope and surgeon experience were significant protective factors in the bivariate analysis. Risk factors identified in the multivariable analysis included greater BMI [odds ratio (OR): 1.03, 95% confidence interval (CI): 1.00, 1.06], blunt force or penetrating trauma (OR: 4.60, 95% CI: 1.86, 11.40), re-opening of prior laparotomy (OR: 6.09, 95% CI: 2.82, 13.17), and bowel leak noted by the surgeon at the time of the index procedure (OR: 3.26, 95% CI: 1.34, 7.92). Emergent cases were associated with a reduced odds of SSI (OR: 0.41, 95% CI: 0.14, 1.18).

Conclusion: Of the NHSN-identified risk factors for SSI following colorectal procedures, only BMI was independently associated with development of SSI. Trauma, re-opening of previous wound, and intraoperative bowel leak were identified as procedure-specific risk factors that could be targeted for focused prevention efforts for SSI after colorectal surgery.