Relationship between Body Mass Index and Outcomes in Microvascular Abdominally Based Autologous Breast Reconstruction

Background: 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: The authors performed a retrospective chart review of all patients who underwent abdominally based autologous free flap breast reconstruction at their institution between 2004 and 2021. Clinical, surgical, and outcomes data were collected. Patients were stratified into five BMI categories: 25, 25.01 to 30, 30.01 to 35, 35.01 to 40, and greater than 40 kg/m(2). Complication rates were analyzed across these groups, and a receiver-operating characteristic analysis was used to determine an optimal BMI cutoff point. Results: A total of 365 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 kg/m(2)), unplanned reoperation (BMI >35 kg/m2), fat necrosis (BMI >40 kg/m(2)), wound breakdown requiring re-operation (BMI >35 kg/m(2)), any infection (BMI >30 kg/m(2)), infection requiring oral antibiotics (BMI >25 kg/m2), infection requiring intravenous antibiotics (BMI >35 kg/m2), and mastectomy flap necrosis (BMI >35 kg/m(2)). The rates of many abdominal complications significantly increased with increasing BMI at distinct levels as well, including delayed wound healing (BMI >30 kg/m(2)), wound breakdown requiring re-operation (BMI >40 kg/m2), any infection (BMI >25 kg/m(2)), and infection requiring oral antibiotics (BMI >25 kg/m(2)). Optimal BMI cutoffs of 32.7 and 30.0 kg/m2 were determined to minimize the occurrence of any breast complication and any abdomen complication, respectively. Conclusions:Preoperative weight loss has great potential to alleviate surgical risk in overweight and obese patients pursuing autologous breast reconstruction. The authors' results quantify the risk reduction based on a patient's preoperative BMI.