Surgical Site Infection Rates according to Patient Risk Index after Cardiovascular Surgery

Choi, Young Hwa; Park, Eun Suk; Chang, Kyeung Hee; Yeom, Joon Sup; Song, Yeung Goo; Chang, Byung; Kang, Meyun Shick; Cho, Bum Koo; Kim, June Myung

Abstract

BACKGROUND
Surveillance of surgical site infection is a main component of nosocomial infection surveillance. To perform a valid comparison of rates among hospitals, among surgeons, across time, surgical site infection rates must account for the variation in patient's underlying severity of illness and other important risk factors. So, a risk index was developed to predict a surgical patient's risk of acquiring a surgical site infection. The risk index score, ranging from 0 to 3, was the number of risk factors present among the following: (1) a patient with an American Society of Anesthesiologists preoperative assessment score of 3,4,5, (2) an operation classified as contaminated or dirty-infected, and (3) an operation lasting over T hours, where T depends upon the operative procedure being performed. METHOD: We performed surgical site infection surveillance according to patient risk index after cardiovascular surgery from Mar 1, 1997 to May 31, 1997. In addition, we also monitored nosocomial infection of all patients after cardiovascular surgery Data was collected prospectively, Surgical site infection rate was classified according to patient risk index and compared with NNIS (National Nosocomial Infections Surveillance) semiannual report of 1995. RESULT: Overall nosocomial infection rate was 18.9% and among all patients detected by surveillance protocols, pneumonia was the most common (6.3%) nosocomial infection after cardiovascular surgery, and the remaining infections were distributed as follows: surgical site infection 45%, urinary tract infection 3.2%, bloodstream infection 3.2%. Surgical site infection rate for patient with scores of 0, 1, 2 and 3 were 0%, 3.1%, 4.6%, 66,7%, respectively and increased according to patient risk index (P<0.05). There is no statistical difference between our surgical site infection rate and 1995 NNIS semiannual report of surgical site infection rates (P>0.05).
CONCLUSION
The patient risk index is a better predictor d surgical site infection risk than the traditional wound classification system and surgical site infection surveillance with patient risk index is useful for nosocomial infection surveillance after surgery.