BMI threshold associates with increased 30-day complications after total thyroidectomy surgery.

BACKGROUND: The relationship between obesity and postoperative complications following total thyroidectomy remains unclear, with prior studies relying on traditional BMI categorizations that may inadequately capture risk. This study aims to define datadriven BMI thresholds associated with 30-day postoperative complications. METHODS: National Surgical Quality Improvement Program (ACS-NSQIP) database (2005-2019). Adult patients undergoing total thyroidectomy (CPT-60240) were included. Stratumspecific likelihood ratio (SSLR) analysis was used to identify BMI thresholds associated with 30-day all-cause complications. Multivariate logistic regression controlled for demographic and clinical confounders. RESULTS: A total of 76,448 patients met inclusion criteria. SSLR analysis identified a BMI threshold of ≥42 as associated with increased complication risk. Patients with BMI ≥42 demonstrated higher rates of all-cause complications (2.22% vs. 1.60%, p=0.001), major complications (1.33% vs. 0.92%, p=0.004), surgical site infections, pulmonary complications, and unplanned reintubation. On multivariate analysis, BMI ≥42 remained an independent predictor of all-cause complications (OR 1.26, 95% CI 1.02-1.55), major complications (OR 1.30, 95% CI 1.00-1.71), and pulmonary complications (OR 1.53, 95% CI 1.14-2.07). CONCLUSION: A BMI threshold of ≥42 is independently associated with increased 30-day morbidity, following total thyroidectomy. These findings support a shift toward data-driven BMI, stratification to improve preoperative risk assessment and perioperative management in thyroid surgery.