The Effect of Body Mass Index on Free Flap Breast Reconstruction

Literature addressing the risks associated with increasing body mass index (BMI) for patients undergoing free flap breast reconstruction is limited. Often, an arbitrary BMI cutoff (i.e., BMI of 30 kg/m²) is used to determine candidacy for a free flap without substantial backing evidence. This study utilized a national multi-institutional database to analyze outcomes of free flap breast reconstruction and stratified complications by BMI class.

Using the 2010 to 2020 National Surgical Quality Improvement Program database, patients who underwent free flap breast reconstruction were identified. Patients were divided into six cohorts based on the World Health Organization BMI classes. Cohorts were compared by basic demographics and complications. A multivariate regression model was created to control for age, diabetes, bilateral reconstruction, American Society of Anesthesiologists class, and operative time.

Surgical complications increased with each BMI class, with the highest rates occurring in class I, II, and III obesity, respectively. In a multivariable regression model, the risk for any complication was significant for class II and III obesity (odds ratio [OR]: 1.23, p < 0.004; OR: 1.45, p < 0.001, respectively). Diabetes, bilateral reconstruction, and operative time were independently associated with an increased risk of any complication (OR: 1.44, 1.14, 1.14, respectively, p < 0.001).

This study suggests that the risks of postoperative complications following free flap breast reconstruction are highest for patients with a BMI greater than or equal to 35 kg/m², having nearly 1.5 times higher likelihood of postoperative complications. Stratifying these risks by weight class can help guide preoperative counseling with patients and help physicians determine candidacy for free flap breast reconstruction.