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Defining a Safe BMI Threshold for Surgery: A NSQIP Analysis of BMI, Comorbidities, and Complication Risk in Plastic Surgery Patients
Mohammed Yamin
*, Shreyas Puducheri, Tricia Mae R. Raquepo, Micaela Tobin, Agustin N. Posso, Samuel J. Lin, Ryan P. Cauley
Plastic and Reconstructive Surgery, Beth Israel Deaconess Medical Center, Boston, MA
Introduction:BMI is a known predictor of surgical complications, but its impact varies by procedure and fat distribution. Obesity with comorbidities increases risk, yet no universal BMI cutoff for safe surgery exists. This study aims to define safe BMI thresholds based on comorbid status and surgical site.
Methods:We analyzed 229,847 cases from ACS-NSQIP, covering 40 plastic surgery procedures. Multivariable logistic regression included BMI (with cubic terms), comorbidities (binary), and body location (from CPT codes) with interaction terms. Outcomes included all complications, wound dehiscence, superficial infection, and DVT/PE. Model performance was evaluated using AIC, McFadden's R, Hosmer-Lemeshow, and 10-fold cross-validated Area Under the Receiver Operating Characteristic curve (AUROC).
Results:BMI significantly predicted complications (beta = 0.381, CI: 0.363-0.398), wound dehiscence (beta = 0.115), superficial infection (beta = 0.140), and DVT/PE (beta = 0.102), all p < 0.001. Nonlinear BMI effects were observed (beta quadratic = -133.91; beta cubic = 209.24). Comorbid status increased risk (beta = 8.01), while BMI's effect was attenuated in comorbid patients (interaction beta = -0.148). Location-specific differences emerged: in breast surgery, BMI had a smaller effect on wound dehiscence (beta = -1.64, p < 0.001). Interaction plots confirmed rising complication probability with BMI, especially in trunk and flap/graft surgeries. Model AUROC was 0.968 (infection) and 0.939 (DVT/PE), supporting strong predictive accuracy.
Conclusion:BMI and comorbidities significantly influence complication risk, with variable impact by surgical site. Findings support procedure- and patient-specific BMI thresholds for safer surgical planning.
