The impact of obesity on the outcomes of 1,153 critically injured blunt trauma patients

Background: Several small series have had mixed conclusions regarding the impact of obesity on outcomes of trauma patients. The purpose of the present study was to evaluate a large cohort of critically injured patients to better understand the influence of obesity on the outcomes of patients after severe blunt trauma. Methods: Retrospective review using the trauma registry and intensive care unit (ICU) database of all blunt trauma patients admitted to the ICU at our urban, Level I trauma center over a 5-year period (1998-2003). Obese patients (body mass index [BMI] ≥ 30 kg/m²) were compared with non-obese patients (BMI < 30 kg/m²). Results: There were 1,153 blunt trauma patients admitted to the ICU during the study period, including 283 (25%) obese (mean BMI = 35 ± 6 kg/m²) and 870 (75%) non-obese (mean BMI = 25 ± 3 kg/m²) patients. There was no difference between groups regarding age, sex, Injury Severity Score, or admission vitals. Obese patients had fewer head injuries (42 versus 55%; p = 0.0001) but more chest (45 versus 38%; p = 0.05) and lower extremity (53 versus 38%; p < 0.0001) injuries. There was no difference in the need for laparotomy, thoracotomy, or craniotomy. Obese patients suffered more complications (42 versus 32%; p = 0.002). Although there was only a trend toward higher mortality in obese patients (22 versus 17%; p = 0.10), stepwise logistic regression revealed obesity as an independent risk factor for mortality (odds ratio, 1.6; 95% confidence interval, 1.0-2.3; p = 0.03). Among survivors, obese patients required longer stays in the hospital (24 ± 21 versus 19 ± 17 days; p = 0.01), the ICU (13 ± 14 versus 10 ± 10 days; p = 0.005), and 2 more days of mechanical ventilation (8 ± 13 versus 6 ± 9 days; p = 0.07). Conclusion: Obese patients incur different injuries after severe blunt trauma than their non-obese counterparts. Despite sustaining fewer head injuries, obese patients suffer more complications, require longer stays in the hospital, more days of mechanical ventilation, and obesity is independently associated with mortality.