The effect of body mass index on posttraumatic transfusion after pelvic trauma

The impact of body mass index (BMI) on posttraumatic blood transfusion after pelvic trauma is not well known. We conducted a retrospective review of trauma registry data over a 5-year period. Patients were stratified by BMI as normal: less than 25 kg/m(2), overweight: 25 to 29.9 kg/m(2), obese: 30 to 39.9 kg/m(2), and morbidly obese: 40 kg/m(2) or greater. Fractures were identified as "likely to receive transfusion" based on literature. Multivariable logistic regression modeling evaluated the relationship between BMI and initial posttraumatic transfusion. A second regression model was created to test the effect of BMI after adjusting for fractures "less likely to receive transfusion." Sixty-six of 244 patients (27.3%) received transfusion (mean: 1.1 ± 2.3 units). Morbid obesity was associated with transfusion (less than 55.6 vs 24.8%; P < 0.05) and units of total blood transfused (2.2 ± 2.9 vs 1.0 ± 2.2 mL; P < 0.05). The average age of patients who received a blood transfusion was significantly older compared with patients who did not receive a transfusion (45.4 ± 18.8 vs 36.1 ± 16.1 years; P < 0.05). After adjusting for potential confounders, morbid obesity was a significant risk factor for transfusion (odds ratio [OR], 4.1; 95% confidence interval [CI], 1.4 to 12.0). Adjusting by age and fracture patterns "less likely to receive transfusion," morbid obesity remained a risk factor for transfusion (OR, 4.5; 95% CI, 1.5 to 12.9). Morbid obesity represented a significant risk factor for posttraumatic transfusion in isolated pelvic trauma, even for fracture patterns "less likely to receive transfusion."