156

Introduction: Surgical site infections (SSI) are a significant source of patient morbidity and hospital cost and have therefore received increasing attention as an outcome measurement of surgical care. Many studies have attempted to define risk factors for SSI but have considered only overall infection rates and have not attempted to categorize risk based on the location of the infection. The purpose of this study was to compare risk factors for the development of wound versus organ-space infections in patients undergoing transabdominal colorectal surgery. Patients and methods: An IRB approved review of a prospectively maintained infection control database was performed examining a 4-year period (1/02-12/05). Patients were included in the database if they had undergone transabdominal operations in which the colon or rectum was repaired or resected, or colostomy was created or revised. Both emergency and elective cases were included. Patients were excluded if the surgical wound was not closed primarily. A standardized definition of wound and organ-space infection was employed to define the main outcome measure. A total of 428 operations were performed that met the inclusion criteria. Statistical comparisons between demographic and clinical variables and wound or organ-space infections were made using chi-square for categorical variables and t-test for normally distributed continuous variables. Forward stepwise logistic regression was used to identify factors independently associated with these outcomes. Results: A total of 105 infections were identified (21%); 73 infections involved the wound and 32 were classified as organ space infections. The univariate determinants of wound infections included, increased body mass index (BMI), creation/revision of colostomy, increased operative time, and increased total fluid given during the operation. Univariate analysis suggested COPD, current smoking habit, creation/revision of colostomy, a reoperative abdomen, transfusion during operation, and increased total amount of colloid given were all significantly associated with organ-space infection. Multivariate analysis suggested that superficial infection was independently associated with increasing BMI (Odds Ratio [OR]=1.07; 95% CI 1.02-1.11) and the creation/revision of colostomy (OR=2.2; 95% CI 1.3-3.9). Organ-space infection was independently associated with transfusion during operation (OR =2.3; 95% CI 1.1-5.5) and a reoperative abdomen (OR=2.5; 95% CI 1.2-5.3). Conclusions: Risk factors for the development infection differed based on the type of SSI being considered. The lack of overlap between factors associated with wound infection and organ-space infection suggests that separate risk models will be required to accurately predict the occurrence of each of these types of infection and that separate strategies will need to be developed to minimize SSIs in each of these locations.