Association of Body Mass Index With In-Hospital Complications After Abdominal Firearm Injury

Background BMI is available early in trauma care, but its association with complications after abdominal firearm injury remains unclear. We evaluated the association between BMI and trauma outcomes in adults with these injuries. Methods We analyzed the 2022 American College of Surgeons Trauma Quality Improvement Program (ACS-TQIP) database. Adults with abdominal firearm injury, abdominal AIS ≥2, and BMI 18.50-44.99 kg/m 2 were stratified by BMI class: normal (18.50-24.99), overweight (25.00-29.99), class I (30.00-34.99), class II (35.00-39.99), and class III obesity (40.00-44.99); sex-interaction effects were assessed. Results Higher BMI was associated with increased in-hospital morbidity despite similar abdominal AIS across BMI groups. Mortality did not differ significantly by BMI category, but hospital length-of-stay was longer among patients with elevated BMI. In adjusted models, class I, class II, and class III obesity were associated with increased odds of AKI, with the greatest odds in class III obesity (OR 3.37; P < 0.001). Overweight, class I obesity, and class II obesity were associated with increased odds of DVT, with the greatest significant odds in class II obesity (OR 1.92; P = 0.005). Severe sepsis was associated with class I obesity (OR 1.65; P = 0.042) and class III obesity (OR 2.78; P = 0.005). BMI category-by-sex interactions were not significant. Discussion Higher BMI across categories is associated with increased thromboembolic, infectious, and renal complications following abdominal firearm injury despite similar or lower anatomic injury severity. BMI may serve as a pragmatic early risk-stratification tool to guide targeted monitoring and prophylaxis in trauma care.