Surgical Site Infection and Colorectal Surgical Procedures: A Prospective Analysis of Risk Factors

Colorectal surgical procedures (CRS) are associated with the highest surgical site infection (SSI) rate among elective operations. A wide range of patient and surgical characteristics have been identified as risk factors for SSI. Most studies are limited by reliance on retrospective data or subset analysis of data that includes CRS. This study reflects analysis of SSI risk factors using prospectively collected data in an elective CRS population.

We analyzed data prospectively collected as part of a randomized, blinded trial of skin anti-sepsis in elective CRS to identify risk factors associated with SSI, including superficial or deep SSI or cellulitis within 30 days post-discharge. Photodocumentation, patient questionnaires, and blinded review by an attending surgeon were used to identify SSI. Multi-variable logistic regression was used to identify factors significantly associated with SSI and to calculate predicted risks of SSI.

From 2011 to 2015, 787 patients undergoing clean-contaminated procedures by colorectal surgeons were analyzed as part of a randomized clinical trial. The overall SSI rate was 21.5%. Four variables-incision length, surgical indication, body mass index, and surgical approach-were significantly associated with SSI. Based on these four variables, the predicted risk of SSI ranges from <5% to >60%.

This study represents the largest prospective investigation of SSI in elective CRS. There is a very wide range of SSI risk after CRS based on both modifiable and non-modifiable factors. Identification of those at the extreme ends of risk may help us both identify and mitigate contributors to infection.