Independent risk factors and a predictive model for surgical site infection following colorectal cancer surgery

Abstract

BACKGROUND

Colorectal cancer (CRC) ranks third in global cancer incidence and second in cancer-related mortality, with surgical resection remaining the cornerstone of curative treatment for localized and advanced disease. Although minimally invasive approaches such as laparoscopy have reduced surgical trauma and accelerated recovery, postoperative complications-particularly surgical site infection (SSI)-remain prevalent due to the anatomical complexity of colorectal surgery, high intraluminal bacterial load, and frequent patient comorbidities including advanced age and malnutrition. SSI delays wound healing, prolongs hospitalization, increases healthcare costs, and may postpone adjuvant therapy, ultimately compromising long-term prognosis. Reported SSI rates vary widely across studies, reflecting differences in surgical techniques, perioperative management, and diagnostic criteria. While multiple factors-such as age, obesity, diabetes, and surgical approach-have been proposed as potential risk contributors, their independent associations and relative weights remain controversial, especially regarding the effect of open vs laparoscopic surgery. Clarifying these independent risk factors is critical for targeted prevention and individualized perioperative management in CRC patients.

AIM

To investigate the incidence of postoperative SSI and associated risk factors in CRC patients.

METHODS

Clinical data were retrospectively collected and analyzed from 228 patients who underwent CRC surgery at the Second Affiliated Hospital of University of South China between January 2021 and May 2025. The incidence of postoperative SSI was calculated. Univariate and multivariate logistic regression analyses were performed to identify risk factors for SSI after CRC surgery. A combined prediction model was constructed, and the predictive performance of individual factors and the model was evaluated using receiver operating characteristic (ROC) curves.

RESULTS

Among the 228 patients, 45 developed postoperative SSI, yielding an overall infection rate of 19.74% (45/228). Among 104 patients who underwent laparoscopic surgery, 11 developed infection, corresponding to an infection rate of 10.58% (11/104); among 124 patients who underwent open surgery, 34 developed infections, corresponding to an infection rate of 27.42% (34/124). Overall, 48 pathogenic strains were isolated from the 45 patients with SSI, including 27 gram-negative bacterial strain (56.25%), 17 gram-positive bacterial strains (35.42%), and four fungal strains (8.33%). Logistic regression analysis identified surgical approach [odds ratio (OR): 16.687, 95%CI: 6.118-45.514], age (OR: 1.071, 95%CI: 1.018-1.126), obesity (OR: 13.895, 95%CI: 2.826-68.320), and incision length (OR: 1.384, 95%CI: 1.183-1.619) as independent risk factors for postoperative SSI in patients with CRC (all SSIs P < 0.05). On ROC curve analysis, the combined prediction model based on these independent risk factors demonstrated high predictive performance (area under the curve = 0.898).

CONCLUSION

Open surgery, advanced age, obesity, and longer incision length were independent risk factors for postoperative SSI in CRC. The combined prediction model based on these factors showed high discriminative value and may help clinicians identify high-risk patients.

Keywords: Colorectal cancer; Postoperative incisional infection; Laparoscopic surgery; Open surgery; Independent risk factors

Core Tip: This retrospective study of 228 patients who underwent colorectal cancer surgery found a postoperative surgical site infection rate of 19.74%, with a lower rate after laparoscopic surgery. Open surgery, advanced age, obesity, and longer incision length emerged as independent risk factors. A prediction model combining these factors showed high discriminatory value (area under the curve = 0.898) for identifying high-risk patients.