High body mass index and smoking predict morbidity in breast cancer surgery: a multivariate analysis of 26,988 patients from the national surgical quality improvement program database.

OBJECTIVE: The purpose of this study was to examine the incidence of complications of breast cancer surgery in a multi-institutional, prospective, validated database and to identify preoperative risk factors that predispose to these complications.

BACKGROUND: There is an increased emphasis on clinical outcomes to improve the quality of surgical care. Although mastectomy and breast conserving surgery have low risk for complications, few US studies have examined the incidence of these complications in large, multicenter patient populations. The broad scale of the National Surgical Quality Improvement Program (NSQIP) data set facilitates multivariate analysis of patient characteristics that predispose to development of postoperative complications in breast cancer surgery.

METHODS: A prospective, multi-institutional study of patients undergoing mastectomy and breast conserving surgery was performed from the National Surgical Quality Improvement Program from 2005 to 2007. Study subjects were selected as a random sample of patients at more than 200 participating community and academic medical centers. Thirty-day morbidity was prospectively collected and the incidence of postoperative complications was determined, with particular emphasis on superficial and deep surgical site infections. Multivariate logistic regression was performed to identify independent risk factors for postoperative wound infections in each.

RESULTS: A total of 26,988 patients were identified who underwent mastectomy (N = 10,471) and breast conserving surgery (N = 16,517). As expected, the overall 30-day morbidity rate for all procedures was low (5.6%), with significantly higher morbidity for mastectomies (4.0%) than breast conserving surgery (1.6%, P < 0.001). The most common complications in all procedures were superficial surgical site infections and deep surgical site infections. Independent risk factors for development of any wound infection in patients undergoing mastectomy were a high body mass index, smoking, and diabetes (ORs = 1.8, 1.6, 1.8). In patients who had a lumpectomy, a high body mass index, smoking, and a history of surgery within 90 days prior to this procedure (ORs = 1.7, 1.9, 2.0) were independent risk factors.

CONCLUSIONS: Although complication rates in breast cancer surgery are low, wound infections remain the most common complication. A high body mass index and current tobacco use were the only independent risk factors for development of a postoperative wound infection across all procedures. This study highlights the benefit of a multi-institutional database in assessing risk factors for adverse outcomes in breast cancer surgery.