Postoperative Outcomes in Prepectoral Versus Retropectoral Immediate Implant-based Breast Reconstruction Across Body Mass Index Categories

Background: Prepectoral (PP) immediate implant-based breast reconstruction (IBBR) is gaining popularity over the retropectoral (RP) breast reconstruction technique. This study aims to compare complication rates across different body mass index (BMI) groups in patients undergoing PP or RP IBBR. Methods: A monocentric retrospective analysis was conducted on patients who underwent mastectomy and IBBR from January 2018 to December 2023. Preoperative characteristics, BMI, type of mastectomy procedure, PP or RR implant placement, and postoperative outcomes were collected and analyzed. Results: A total of 217 patients were included, representing 276 IBBRs. The overall complication rate on a per breast basis was 26.4%. The overall complication rate did not differ across BMI groups ( P = 0.314) and between PP and RP IBBR ( P = 0.8083). In the PP group, anemia rate increased with low BMI (odds ratio [OR] 0.0215, P = 0.033) and skin complications were more frequent with higher BMI (OR 0.0428, P = 0.0389). In the RP group, higher BMI was correlated with a higher seroma rate in the RP IBBR group (OR 1.2045, P = 0.0334) and a longer hospital length of stay (coefficient 0.248, adjusted R ² 0.082, SD 0.098, P = 0.014). Conclusions: PP IBBR was associated with a significantly higher rate of anemia in patients with low BMI, and a significantly higher rate of skin complications in high BMI. RP IBBR was associated with higher seroma rate and longer hospital length of stay in patients with higher BMI.