Obesity in trauma patients: correlations of body mass index with outcomes, injury patterns, and complications

Current understanding of the effects of obesity on trauma patients is incomplete. We hypothesized that among older trauma patients, obese patients differ from nonobese patients in injury patterns, complications, and mortality. Patients older than 45 years old presenting to a Level I trauma center were included in this retrospective database analysis (n = 461). Body mass index (BMI) groups were defined as underweight less than 18.5 kg/m(2), normal 18.5 to 24.9 kg/m(2), overweight 25.0 to 29.9 kg/m(2), or obese greater than 30 kg/m(2). Injury patterns, complications, and outcomes were analyzed using univariate analyses, multivariate logistic regression, and Kaplan-Meier survival analysis. Higher BMI is associated with a higher incidence of torso injury and proximal upper extremity injuries in blunt trauma (n = 410). All other injury patterns and complications (except anemia) were similar between BMI groups. The underweight (BMI less than 18.5 kg/m(2)) group had significantly lower 90-day survival than other groups (P < 0.05). BMI is not a predictor of morbidity or mortality in multivariate analysis. Among older blunt trauma patients, increasing BMI is associated with higher rates of torso and proximal upper extremity injuries. Our study suggests that obesity is not an independent risk factor for complications or mortality after trauma in older patients. Conversely, underweight trauma patients had a lower 90-day survival.