With rising obesity rates in the United States, knowledge of obesity's impact on trauma outcomes is essential to providing high-quality care. The interaction between body mass and outcomes is unclear, with existing literature demonstrating conflicting results. We hypothesized that in a broad cohort of trauma patients, obesity would be associated with in-hospital mortality.

We conducted a retrospective cohort study using the 2014-2015 Pennsylvania Trauma Outcomes Study (PTOS) registry, a state-wide registry to which all accredited Pennsylvania trauma centers are required to report. We included nonburn adult trauma patients admitted to level I and II centers. Because PTOS lacks height data, weight thresholds of 111.75 kg for men and 95.05 kg for women were used, which correspond to BMI = 30 kg/m² at the 99th height percentile in the United States. We tested the association of obesity with in-hospital mortality using logistic regression to adjust for confounders.

We included 46,329 patients in a complete case analysis. In univariate logistic regression analysis, injury mechanism, presence of a complication, age, sex, need for blood transfusion, Revised Trauma Score, and Injury Severity Score were associated with mortality. On multivariate analysis, including these factors, obesity was significantly associated with mortality (odds ratio 1.36, 95% confidence interval 1.10-1.69). Respiratory, thromboembolic, and infectious complications, as defined by PTOS, were more common in obese patients.

After adjusting for patient and injury characteristics, obesity is associated with increased mortality following trauma. This information may help resolve previous conflicting evidence and guide providers in caring for the obese patient.