Defining BMI Thresholds for Free Flap Reconstruction Following Nipple-Sparing Mastectomy

Autologous breast reconstruction (ABR) following nipple-sparing mastectomy (NSM) is recognized for superior aesthetic outcomes. However, body mass index (BMI)-based recommendations for free flap reconstruction remain debated due to the risk of perioperative complications. This study assesses outcomes concerning BMI, defining optimal BMI cutoffs for patients undergoing ABR after NSM.

A retrospective review of free flap breast reconstruction following NSM from 2005 to 2024 was performed. Patient BMI was utilized as a predictor of complications post-NSM with ABR. Considering demographic and comorbidity factors, risk-adjusted logistic regression models evaluated the BMI-outcome relationship. Receiver operating characteristic (ROC) curves defined BMI cutoffs. Youden's Index identified optimal BMI cutoffs.

A total of 301 patients (466 breasts) underwent free flap breast reconstruction following NSM. The median BMI was 27.8 kg/m² ± 5.3. Nipple areolar complex (NAC) necrosis was observed in 4.8% of the cases, with an AUC of 0.7195 and a BMI threshold of 37.6. The rates, AUC values, and BMI cutoffs for other complications included: 1.7% seroma rate (AUC: 0.8352, BMI: 41.1), 3.4% hematoma rate (AUC: 0.700, BMI: 39.2), and 11.8% skin necrosis rate (AUC: 0.6878, BMI: 34). Flap loss due to vascular complications was observed in 0.9% of patients, with an AUC of 0.7308 and a BMI cutoff of 43.2.

This study quantifies the significance of BMI in determining postoperative complications after NSM with free flap breast reconstruction. ABR after NSM is broadly safe across most BMI values, with progressively higher risk primarily at very high BMI. Prudent consideration of BMI cutoffs can reduce postoperative morbidity. This data offers surgeons BMI thresholds for improved patient counseling, surgical planning, and outcome optimization.