Relationship Between BMI and Outcomes in Microvascular Abdomen-Based Autologous Breast Reconstruction

Introduction: Increasing body mass index (BMI) is a known risk factor for autologous microsurgical breast reconstruction. No prior studies have stratified outcomes across BMI ranges or defined the BMI at which complication rates dramatically increase. Methods: We performed a retrospective chart review of all patients who underwent abdomen-based autologous free flap breast reconstruction at our institution between 2004-2021. Clinical, surgical and outcomes data were collected. Patients were stratified into five BMI categories: ≤25, 25.01-30, 30.01-35, 35.01-40 and >40. Complication rates were analyzed across these groups, and a receiver-operating characteristic analysis was used to determine an optimal BMI cutoff point. Results: Three hundred and sixty-five patients (545 breasts) were included in this study. The rates of several breast complications significantly increased with increasing BMI at distinct levels, including any breast complication (BMI>30), unplanned re-operation (BMI>35), fat necrosis (BMI>40), wound breakdown requiring re-operation (BMI>35), any infection (BMI>30), infection requiring PO antibiotics (BMI>25), infection requiring IV antibiotics (BMI>35), and mastectomy flap necrosis (BMI>35). The rates of many abdominal complications significantly increased with increasing BMI at distinct levels as well, including delayed wound healing (BMI>30), wound breakdown requiring re-operation (BMI>40), any infection (BMI>25), and infection requiring PO antibiotics (BMI>25). Optimal BMI cutoffs of 32.7 and 30.0 were determined to minimize the occurrence of any breast complication and any abdomen complication, respectively. Conclusion: Pre-operative weight loss has great potential to alleviate surgical risk in overweight and obese patients pursuing autologous breast reconstruction. Our results quantify the risk reduction based on a patient’s pre-operative BMI.