An audit of risk factors for wound infection in patients undergoing coronary artery bypass grafting or valve replacement.

ABSTRACT

OBJECTIVES: To investigate the epidemiology of surgical site infection in cardiac surgery patients operated on in 2006. DESIGN: Retrospective study of a case-control sample. SETTING: Cardiac surgery unit of a university teaching hospital in Hong Kong. PATIENTS Cardiac surgery patients with surgical site infection were matched by procedure type, sex, and year of surgery with non-infected patients. MAIN OUTCOME MEASURES: Identification of risk factors for surgical site infection. RESULTS: The infected and non-infected cardiac surgery patients did not differ in age, sex, or smoking history; however, patients with surgical site infection were significantly heavier (mean body mass index, 26.6 vs 23.9 kg/m2, P < 0.046). Almost 41% of the subjects had a history of diabetes mellitus, there being a significantly greater proportion among infected than non-infected patients (53.1% vs 28.1%, P < 0.042). All 37 of the patients without a diagnosis of diabetes had normal (ie < 8 mmol/L) preoperative glucose levels, but 99% of them yielded evidence of subsequent glycaemic dysfunction during or after surgery. Overall, 50% of the patients had a blood transfusion during the operation, with infected patients significantly more likely to have been transfused than the non-infected ones (65.6% vs 34.4%, P < 0.008). CONCLUSIONS: There appears to be a relationship between surgical site infection in cardiac surgery patients and pre-existing (diagnosed and covert) diabetes mellitus and blood transfusion. Future studies should consider these factors in relation to surgical site infections, both in the wider surgical population and from a risk-minimisation perspective.