Risk factors for surgical site infection in a teaching hospital: a prospective study of 1,138 patients

Abstract

Background: The purpose of this study was to identify risk factors for surgical site infection (SSI) in a teaching hospital.

Methods: A prospective study was initiated to investigate risk factors for SSI at a university-affiliated tertiary care center from July 2013 to December 2014. The chi-square test for categorical variables was used to determine the significance of association, whereas the multivariate logistic regression model was used to examine independent risk factors for SSI.

Results: A total of 1,138 patients met the inclusion criteria, in whom 36 cases of infection occurred during the hospitalization period and two cases occurred after discharge. Univariate analysis showed that SSI was associated with the type of operation, wound classification, volume of blood loss, blood transfusion, American Society of Anesthesiology score before surgery, risk index, duration of surgery, diabetes, cancer, gastrointestinal catheter, urinary catheter, postoperative drainage, and preprocedural white blood cell count. Multivariate analysis identified six independent parameters correlating with the occurrence of SSI: diabetes (odds ratio [OR] 6.400; 95% confidence interval [CI] 2.582-15.866; P=0.000); cancer (OR 2.427; 95% CI 1.028-5.732; P=0.043); preprocedural white blood cell count more than 10×10(9)/L (OR 6.988; CI 3.165-15.425; P=0.000); wound classification (clean contaminated [OR: 7.893; CI: 2.244-27.762; P=0.001]; contaminated [OR: 7.031; CI: 1.652-29.922; P=0.008]; dirty [OR: 48.778; CI: 5.418-439.164; P=0.001]); operative duration more than 120 minutes (OR 4.289; CI 1.773-10.378; P=0.001); and postoperative drainage (OR 3.957; CI 1.422-11.008; P=0.008).

Conclusion: Our data suggest that all these risk factors could be regarded as potential indicators of SSI and that relevant preventive measures should be taken to reduce SSI and improve patient outcomes.

Keywords: nosocomial infection; risk factors; surgical site infection; wound classification.