Predictive factors for early- and late-onset surgical site infections in patients undergoing elective colorectal surgery. A multicentre, prospective, cohort study.

Background: Surgical site infections (SSIs) are the leading cause of healthcare-associated infections in acute care hospitals in Europe. However, the risk factors for the development of early-onset (EO) and late-onset (LO) SSI have not been elucidated.

Aim: This study investigated the predictive factors for EO-SSI and LO-SSI in a large cohort of patients undergoing colorectal surgery.

Methods: We prospectively followed-up adult patients undergoing elective colorectal surgery in 10 hospitals (2011-2014). Patients were divided into three groups: EO-SSI, LO-SSI, or no infection (no-SSI). The cut-off defining EO-SSI and LO-SSI was seven days (median time to SSI development). Different predictive factors for EO-SSI and LO-SSI were analysed, comparing each group with the no-SSI patients.

Findings: Of 3701 patients, 320 (8.6%) and 349 (9.4%) developed EO-SSI and LO-SSI, respectively. The rest had no-SSI. Patients with EO-SSI were mostly males, had colon surgery and developed organ-space SSI whereas LO-SSI patients frequently received chemotherapy or radiotherapy and had incisional SSI. Male sex (odds ratio (OR): 1.92; P < 0.001), American Society of Anesthesiologists' physical status >2 (OR: 1.51; P = 0.01), administration of mechanical bowel preparation (OR: 0.7; P = 0.03) and stoma creation (OR: 1.95; P < 0.001) predicted EO-SSI whereas rectal surgery (OR: 1.43; P = 0.03), prolonged surgery (OR: 1.4; P = 0.03) and previous chemotherapy (OR: 1.8; P = 0.03) predicted LO-SSI.

Conclusion: We found distinctive predictive factors for the development of SSI before and after seven days following elective colorectal surgery. These factors could help establish specific preventive measures in each group.