Body mass index as a continuous predictor of outcomes after expander-implant breast reconstruction

Background: Studies show that obesity is a risk factor for complications after expander/implant breast reconstructions. However, reports vary on the precise threshold of body mass index (BMI) as a predictor of heightened risk. We endeavored to link BMI as a continuous variable to overall complications in a single-surgeon series of expander-implant reconstructions. Methods: From 399 patients undergoing expander-implant reconstruction, 551 breasts were stratified to normal weight, overweight, and obese groups for analysis and comparison with previous studies. Logistic regression was performed to predict changes to risk profile per increment of BMI. Results: Complication rates for obese and overweight patients were significantly greater than for normal weight patients, that is, 21.1% and 24.0% versus 10.4%, respectively (P < 0.005). A unit increase in BMI predicted a 5.9% increase in the odds of a complication occurring, and 7.9% increase in the odds of reconstruction ending in failure. Conclusions: By expanding the analysis of BMI to include patients who do not meet the traditional definition of obesity (BMI 30 kg/m), we demonstrated that simply overweight patients (25 ≤ BMI < 30 kg/m) had an elevated complication rate. Moreover, through regression analysis, we established that BMI as a continuous variable predicts outcomes from expander-based breast reconstruction.