Risk Stratification for Surgical Site Infections in Colon Cancer

Abstract

Importance: Surgical site infections (SSIs) feature prominently in surgical quality improvement and pay-for-performance measures. Multiple approaches are used to prevent or reduce SSIs, prompted by the heavy toll they take on patients and health care budgets. Surgery for colon cancer is not an exception.

Objective: To identify a risk stratification score based on baseline and operative characteristics.

Design, setting, and participants: This retrospective cohort study included all patients treated surgically for colon cancer at Massachusetts General Hospital from 2004 through 2014 (n = 1481).

Main outcomes and measures: The incidence of SSI stratified over baseline and perioperative factors was compared and compounded in a risk score.

Results: Among the 1481 participants, 90 (6.1%) had SSI. Median (IQR) age was 66.9 (55.9-78.1) years. Surgical site infection rates were significantly higher among people who smoked (7.4% vs 4.8%; P = .04), people who abused alcohol (10.6% vs 5.7%; P = .04), people with type 2 diabetics (8.8% vs 5.5%; P = .046), and obese patients (11.7% vs 4.0%; P < .001). Surgical site infection rates were also higher among patients with an operation duration longer than 140 minutes (7.5% vs 5.0%; P = .05) and in nonlaparoscopic approaches (clinically significant only, 6.7% vs 4.1%; P = .07). These risk factors were also associated with an increase in SSI rates as a compounded score (P < .001). Patients with 1 or fewer risk factors (n = 427) had an SSI rate of 2.3%, equivalent to a relative risk of 0.4 (95% CI, 0.16-0.57; P < .001); patients with 2 risk factors (n = 445) had a 5.2% SSI rate (relative risk, 0.78; 95% CI, 0.49-1.22; P = .27); patients with 3 factors (n = 384) had a 7.8% SSI rate (relative risk, 1.38; 95% CI, 0.91-2.11; P = .13); and patients with 4 or more risk factors (n = 198) had a 13.6% SSI rate (relative risk, 2.71; 95% CI, 1.77-4.12; P < .001).

Conclusions and relevance: This SSI risk assessment factor provides a simple tool using readily available characteristics to stratify patients by SSI risk and identify patients at risk during their postoperative admission. Thereby, it can be used to potentially focus frequent monitoring and more aggressive preventive efforts on high-risk patients.