Direct Observations of Surgical Wound Infections at a Comprehensive Cancer Center

Abstract

To identify the rate of surgical site infection and risk factors for surgical site infection in patients with cancer and to evaluate antibiotic use patterns on surgical oncology services. Criterion standard. Memorial Sloan-Kettering Cancer Center, a comprehensive cancer center at a university hospital. Over a 15-month period, 1226 patients undergoing 1283 surgical procedures performed by the Breast, Colorectal, and Gastric-Mixed Tumor surgical services. Direct observation of surgical sites was performed by a single, surgeon-trained member of the hospital's Infection Control Section, adhering to an established protocol for grading of the surgical site. Operative procedures accounted for the following traditional wound class distributions: class I (clean), 630 cases; class II (clean-contaminated), 577 cases; class III (contaminated), 29 cases; and class IV (dirty-infected), 47 cases. Surgical site infection rates were 3.8% in class I; 8.8% in class II; 20.7% in class III; and 46.9% in class IV procedures. The mean (+/- SD) age was 57.7 +/- 14.3 years and the Anesthesiology Society of America physical assessment score, 2.3 +/- 0.7. The mean (+/- SD) operation time was 145 +/- 104.9 minutes. Logistic regression analysis demonstrated several risk factors for surgical site infection: obesity (P < .0001); a contaminated or dirty-infected surgical procedure category (P < .0001); operation time greater than 4 hours (P = .0004); Anesthesiology Society of America physical assessment score of 3 or greater (P < .01); and preoperative length of stay of 3 or more days (P = .03). Risk factors for surgical site infection in patients with cancer are similar to those found in the National Nosocomial Infections Surveillance System. However, as an individual risk factor among our patient population, obesity contributed as strongly as the surgical procedure category to a patient's likelihood of acquiring a surgical site infection. In addition to Anesthesiology Society of America status, length of the surgical procedure, and surgical procedure category, obesity should warrant consideration as an individual risk factor for surgical site infection.