Complication Risk after Autologous Reconstruction Stratified by BMI Classification

Background: Numerous studies have identified patient-related factors associated with increased risk of surgical complications. This study sought to update the current literature on the effect of body mass index (BMI) on complication rates after autologous breast reconstruction. Methods: An IRB-approved retrospective review of women who underwent abdominally based autologous breast reconstruction at a single NCI-designated cancer center from 2010-2022 was performed. Most patients underwent deep inferior epigastric artery perforator (DIEP) flap reconstruction, however patients who underwent muscle-sparing transverse rectus abdominis muscle (ms-TRAM) and superficial inferior epigastric artery (SIEA) flaps were also included. Reconstructions were stratified by BMI classification: underweight (BMI < 18.5), normal weight (18.5-24.9, overweight (BMI 25-29.9), class I obesity (BMI 30-34.9), class II obesity (BMI 35-39.9), class III obesity (40+). Rates of systemic, donor and recipient site complications were assessed, as well as rates of readmission and reoperation within 90 days. Results: 2,231 patients with abdominally based autologous breast reconstruction were included. 28 (1.3%) patients were underweight, 754 (33.8%) were normal weight, 887 (39.8%) were overweight, and 562 (25.2%) were obese. Most obese patients were categorized as class I (435 patients; 77.4%), however 103 (18.3%) and 24 (4.3%) of the obese patients were class II and III, respectively. On univariate analysis, there were significant differences between BMI groups for race, ethnicity, receipt of chemotherapy, timing of reconstruction, laterality, mesh use, midline plication, diabetes and hypertension. Complications were assessed as a composite measure and separately. Rates of overall complications differed between BMI groups (p<0.001), as did rates of specific complications, including mastectomy skin flap or nipple necrosis (p<0.001), wound complications (p<0.001), infection (p<0.001), seroma (p=0.007), readmission (p=0.006), and reoperation within 90 days (p=0.011). The proportion of patients with complications increased as BMI increased. When controlling for other variables in a multivariable logistic regression model, having a higher BMI (Odds Ratio (OR): 1.03, 95% Confidence Interval (CI): 1.01, 1.05; p=0.002), receiving adjuvant radiation (OR: 1.55, 95% CI: 1.04, 2.33; p=0.032), and having comorbid cardiovascular disease (OR: 1.70, 95% CI: 1.36, 2.12; p<0.001) were associated with having postoperative complications. Conclusion: Successful autologous reconstruction was achieved in the majority of patients; however, our results indicate that obesity status continues to be associated with an increased risk of overall and specific complications including readmission and reoperation within 90 days.