Background: Global parameters, such as wound class, the American Society of Anesthesiologists' physical classification score, and prolonged operative time, have been associated with the risk of surgical site infection (SSI). We hypothesized that additional risk factors for SSI would be identified by controlling for these parameters and that deep and organ/space SSI may have different risk factors for occurrence.
Methods: A retrospective review was performed on general and vascular surgical patients who underwent an operation between June 2000 and June 2006 at a single institution. Patients with SSI were matched with a case-control cohort of patients without infection (no SSI) according to age, sex, ASA score, wound class, and type of operative procedure. Data were analyzed using bivariate and regression analyses.
Results: Overall, 10,253 general surgical procedures were performed during the 6-year period; 316 patients (3.1%) developed SSI. In all, 300 patients with 251 superficial (83.6%), 22 deep (7.3%), and 27 organ/space (9%) SSIs were matched for comparison. Multivariate logistic regression analysis identified previous operation (odds ratio [OR], 2.4; 95% confidence interval [CI] = 1.6-3.7), duration of operation >or=75th percentile (OR, 1.8; 95% CI = 1.2-2.8), hypoalbuminemia (OR, 1.8; 95% CI = 1.1-2.8), and a history of chronic obstructive pulmonary disease (OR, 1.7; 95% CI = 1.0-2.8) as independent risk factors for SSI. Only hypoalbuminemia (OR, 2.9; 95% CI = 1.4-6.3) and a previous operation (OR, 2.0; 95% CI = 1.0-4.4) were significantly associated with deep or organ/space infections.
Conclusions: These results demonstrate additional factors that increase the risk of developing SSI. Deep and organ/space infections have a different risk profile. This information should guide clinicians in their assessment of SSI risk and should identify targets for intervention to decrease the incidence of SSI.