Comparison of the incidence and predicted risk of early surgical site infections after breast reduction.

In plastic surgery, clean, elective operations such as breast reductions are anticipated to have low risk factors for infections (1.1-2.1%). To further lower or prevent surgical site infections (SSI), the efficacy of a prophylactic administration of anti-microbacterials remains a current controversial issue in plastic surgery. We report here the findings of a retrospective study in which we examined two groups of patients with breast reductions, one of which received a single-shot antimicrobacterial prophylaxis with cefuroxime preoperatively and the other who were given no anti-microbacterials. The aims were to determine the early SSI incidence of both groups, to classify breast reductions with respect to their inherent SSI risk by two widespread, combined risk scores, i.e., the National Nosocomial Infection Surveillance (NNIS) score and the Study on the Efficacy of Nosocomial Infection Control (SENIC) score, and to compare the actual SSI incidence to the predicted risk of the scores. In the divisions of plastic surgery at two hospitals, 153 patients (group I) and 136 patients (group II) could be included in the study in the 4-year period April 1997 to December 2001. Excluded were all patients with unilateral breast reduction or breast reconstruction and patients who were followed up less than 30 days postoperatively. The two groups were comparable with respect to demographic and clinical features such as age and risk factors, and there were no detectable significant intergroup differences in the general perioperative data. According to the NNIS and the SENIC scores, all operations were "clean," and the American Society of Anesthesiologists (ASA) score was < 3 in all patients. Although the mean duration of the operation was significantly different in the two groups (190 min in group I, 160 min in group II; p < 0.001, Mann-Whitney test; 75th percentile at and 4 and 3 h, respectively), it was longer than 2 h in both groups. The incidence of early infections was 3.9% in the first group, compared with 3.6% in the second group (p = 1.0, odds ratio = 1.07, 95% CI = 0.32-3.6). All infections were local and superficial; no general symptoms were noticed. Three patients had to be readmitted and two of these were reoperated. The rate of infections for both groups was higher than generally anticipated for this kind of clean operations and higher than predicted by the NNIS score for medium risk (predicted risk of 2.9%). The reason for this discrepancy is that the NNIS score is an inpatient risk score which does not include a postdischarge SSI surveillance. Using the NNIS definition of SSI we would have had an infection rate of 0% in both groups in our study. According to the SENIC score, breast reductions can be classified also as medium risk of SSI with a predicted risk of 3.9%, which showed a nearly perfect correspondence with the actual SSI incidence in both study groups. The reason for this increased, medium risk is the factor "operation time > 2 h," which is obviously an inherent risk factor in breast reductions. Among the multitude of patient and nonpatient SSI risk factors, in healthy women operation time was the only factor which could be clearly identified.