Risk factors for prediction of surgical site infections in “clean surgery”

Background The aim of this study was to determine the risk factors of surgical site infections (SSI) in clean surgery and to identify high- and low-risk patients from whom efficacy of the antibiotic prophylaxis was analyzed. Methods From June 1982 to September 1996, a database was established from 3 prospective multicenter randomized studies, containing information of 5798 patients who underwent abdominal noncolorectal surgery. Multivariate analysis was performed using nonconditional logistic regression expressed as an odds ratio (OR). Results A total of 2374 patients underwent a clean surgery. An antibiotic prophylaxis was administered to 1943 patients (81.8%). A multivariate analysis was performed including only preoperative factors and disclosed 3 independent factors: cirrhosis (OR, 2.8; 95% CI: 1.6-12.8), other disease (OR, 2.7; 95% CI: 1.3-5.8), and preoperative urinary catheter (OR, 2.1; 95% CI: 1.1-4.6). A risk score for SSI was constructed: −4.9 + (1.5 × cirrhosis†) + (other disease†) + (0.8 × preoperative urinary catheter†) († = 0 if absent or 1 if present). The study included 1 group of patients having no risk factors for SSI with a score below −4.5 (S1R−) and 1 group of patients having 1 or more risk factors for SSI with a score over −4.5 (S1R+). Antibiotic prophylaxis did not reduce the infectious complication rate in the S1R− group, whereas, in the S1R+ group, it reduced significantly the rate of SSI and of parietal infectious complications by 58% and 69%, respectively. Conclusions Antibiotic prophylaxis in clean abdominal surgery was effective in high-risk patients. Urinary catheter must be avoided.