RESUMO
BACKGROUND: Multisite information regarding surgical site infection (SSI) rates for cardiac surgery programmes is not widely available. Ward characteristics that may affect outcomes have not been analysed previously. AIM: To determine individual- and ward-level factors associated with SSI occurrence after coronary artery bypass grafting (CABG) and valvular surgery. METHODS: A dataset from the French national SSI database ISO-RAISIN 2008-2011 was used. Only adult patients were included. A standardized questionnaire was completed for each patient who underwent surgery, and patients with and without SSI were characterized. Patients and ward risk factors for SSI were analysed using a multilevel logistic regression model with SSI as binary outcome (two levels: patient and ward). RESULTS: Out of 8569 patients from 39 wards, the SSI rate was 2.2%. Micro-organisms were isolated in 144 patients (74%): 35% coagulase-negative staphylococci (N = 51), 23% Staphylococcus aureus (N = 33), 6% Escherichia coli (N = 8). Higher probability of SSI was associated with the duration of preoperative hospitalization, the duration of follow-up, the duration of surgery >75th percentile and the SSI rate in the surgery ward. The residual heterogeneity between wards (median odds ratio: 1.53) was as relevant as duration of preoperative hospitalization (odds ratio: 1.57). CONCLUSION: Although patient risk factors were more strongly associated with SSI occurrence, this study provided evidence for the existence of a ward-level effect. This should be taken into account when considering possible corrective interventions.