Underweight BMI values and their influence on prosthetic breast reconstruction 30-day outcomes

Background: Risk factors for breast reconstruction have been widely studied. However, the impact of underweight BMI values on outcomes has not yet been examined. Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was retrospectively reviewed for all patients who underwent prosthetic breast reconstruction between 2006 and 2011. Underweight (BMI<18.5) and normal weight (reference, BMI 18.5-24.99) patients were included in the final analysis. Multivariate logistic regression models were used to determine independent predictors of complications. Results: The underweight and normal weight patient cohorts were well-matched. When compared to the normal weight population, underweight patients displayed decreased rates of total complications, surgical complications, and reoperation. On multivariate analysis, patients with a BMI in the underweight category trended toward lower risk for total and surgical complications. The sum of total relative value units (RVUs) was a significant risk factor for total complications (OR 1.014, p=0.047). Conclusion: Through this analysis of over 1,600 patients, we reveal that underweight patients (BMI<18.5) receiving prosthetic breast reconstruction did not have any significant differences in adverse events than their normal weight counterparts. As more patients are collected in NSQIP, it will be possible to delineate between those with underweight due to lean body mass versus chronic diseases, allowing more granular analysis of the relationship between underweight status and outcomes after breast reconstruction.