Impact of a surgeon-trained observer on accuracy of colorectal surgical site infection rates

PURPOSE: The aims of this study were 1) to establish accurate and reproduci ble baseline surgical site infection rates for our department and 2) to ide ntify risk factors associated with surgical site infection in patients unde rgoing surgery on a colorectal service. METHODS. Phase I-Surgical site infe ction grading between the surgeon-trainer and the observer-trainee was vali dated using a four-point scale for wound evaluation previously used by our institution. Phase II-Patients undergoing colorectal surgery were prospecti vely monitored. The observed surgical site infection rate was compared with morbidity and mortality reports. Patient and perioperative variables were analyzed for their effect on surgical site infection using the chi-squared test. Risk factors approaching significance on univariate analysis (P < 0.2 ) were entered into a multivariate stepwise logistic regression model. RESU LTS: Concordance on surgical site infection grading between the surgeon-tra iner and the observer-trainee improved from an initial 79 percent to 96 per cent during the validation period. The surgeon-trained observer reported a surgical site infection rate of 7.2 percent vs. a morbidity and mortality r eported rate of 3.3 percent. Among the variables examined, obesity and surg ical procedure category were significantly associated with surgical site in fection rates. The effect of prophylactic antibiotics and prior chemotherap y, radiation, or steroid therapy on surgical site infection rates approache d significance. A logistic regression analysis incorporating these risk fac tors for surgical site infection accurately predicted infection status 93 p ercent of the time. CONCLUSION. Use of a surgeon-trained observer doubles t he detection rate of postoperative surgical site infection. Accurate, prosp ective assessment identifies risk factors significantly associated with inc reased surgical site infection rates in colorectal surgical patients.