An Evaluation of Surgical Site Infections by Wound Classification System Using the ACS-NSQIP

Background. Surgical wound classification has been the foundation for infectious risk assessment, perioperative protocol development, and surgical decision-making. The wound classification system categorizes all surgeries into: clean, clean/contaminated, contaminated, and dirty, with estimated postoperative rates of surgical site infection (SSI) being 1%-5%, 3%-11%, 10%-17%, and over 27%, respectively. The present study evaluates the associated rates of the SSI by wound classification using a large risk adjusted surgical patient database. Methods. A cross-sectional study was performed using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) dataset between 2005 and 2008. All surgical cases that specified a wound class were included in our analysis. Patient demographics, hospital length of stay, preoperative risk factors, co-morbidities, and complication rates were compared across the different wound class categories. Surgical site infection rates for superficial, deep incisional, and organ/space infections were analyzed among the four wound classifications using multivariate logistic regression. Results. A total of 634,426 cases were analyzed. From this sample, 49.7% were classified as clean, 35.0% clean/contaminated, 8.56% contaminated, and 6.7% dirty. When stratifying by wound classification, the clean, clean/contaminated, contaminated, and dirty wound classifications had superficial SSI rates of 1.76%, 3.94%, 4.75%, and 5.16%, respectively. The rates of deep incisional infections were 0.54%, 0.86%, 1.31%, and 2.1%. The rates for organ/space infection were 0.28%, 1.87%, 2.55%, and 4.54%. Conclusion. Using ACS-NSQIP data, the present study demonstrates substantially lower rates of surgical site infections in the contaminated and dirty wound classifications than previously reported in the literature. (C) 2012 Elsevier Inc. All rights reserved.