Effect of body mass index in perioperative outcomes in free-flap breast reconstruction surgery.

[BACKGROUND] Studies evaluating the eligibility of patients with high body mass index (BMI) for free-flap breast reconstruction remain limited. Using a large retrospective database, we analyzed perioperative risks to assess the suitability of the BMI cutoff of 35 individuals for surgical candidacy.

[METHODS] This retrospective study used data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) from 2016 to 2022. Patients with breast cancer who underwent free-flap breast reconstruction were stratified into six BMI categories and assessed for perioperative outcomes such as postoperative complications, unplanned return to the operating room (OR), length of hospital stay, and readmission rate. These outcomes were compared between BMI≤35 and BMI>35 kg/m using bivariate and multivariate regression analyses.

[RESULTS] Among 15,364 patients who underwent free-flap breast reconstruction, 16.9% had a BMI≥35 kg/m, including 3.2% with BMI 40-45 kg/m and 1.0% with BMI>45 kg/m. Overall complication rates more than doubled with increasing BMI from 9.3% among BMI<25 to 20.7% among BMI≥45 kg/m. Similarly, venous thromboembolism risk rose from 0.4% in patients with BMI<25 kg/m to 4.0% in those with BMI≥45 kg/m. Compared to patients with BMI≤35 kg/m, those with BMI>35 kg/m had significantly higher complication rates (11.6% vs. 17.2%; P<0.001), longer hospital stays (3.5 day vs. 3.8; p<0.001), increased unplanned return to OR (10.5% vs. 14.9%; p<0.001), and higher readmission rates (4.9% vs. 9.4%; p<0.001). Multivariate regression analyses, adjusted for age, comorbidities, and surgical characteristics (unilateral vs. bilateral and immediate vs. delayed reconstruction) identified BMI>35 kg/m as an independent risk factor for overall complication rates (adjusted odd's ratio [AOR]=1.47), unplanned return to OR (AOR=1.40), and readmission (AOR=1.88).

[CONCLUSION] This study demonstrated that BMI>35 kg/m is an independent risk factor associated with worse perioperative outcomes after free-flap breast reconstruction. Although not a contraindication, surgeons should counsel patients about the risks and consider referring them to weight loss programs before surgery if time permits. Preoperative weight loss may help, but further studies are needed to determine its impact on outcomes.