Increasing BMI is associated with higher mortality, worsening outcomes and highly specific injury patterns following trauma: A multi-institutional analysis of 191,274 patients.

ABSTRACT

BACKGROUND: As the prevalence of obesity has increased, trauma centers are faced with managing this expanding demographics' unique care requirements. Research on the effects of body mass index (BMI) in trauma patients remains conflicting. This study aims to evaluate the impact of BMI on patterns of injury and patient outcomes following trauma. METHODS: Patients from 87 hospitals' trauma registries were selected. Those missing height, weight, disposition, or who died in the emergency department were excluded. The BMI categories were calculated from admission height and weight and verified against the electronic medical records. Patients were grouped by the National Institutes of Health-defined obesity class and compared by rate of mortality and in-hospital complications. Logistic regression was used to estimate associations, adjusting for age, gender, race, Injury Severity Score, and number of comorbidities. RESULTS: There were 191,274 patients, 53% male; mean age was 60.4 years, mean Glasgow Coma Scale score 14.4, mean Injury Severity Score of 8.8, and 40.4% normal weight. Increased BMI was associated with an injury pattern of increased rates of extremity fractures (humerus, femur, tibia/fibula) and decreased rates of hip fractures and head injuries. Compared with the normal weight group, patients were more likely to die if they were Underweight (adjusted odds ratio [AOR], 1.18; 95% confidence interval [CI], 1.01-1.38), obese class II (AOR, 1.24; 95% CI, 1.07-1.45), or obese class III (AOR, 1.55; 95% CI, 1.29-1.87). Obese class III was associated with higher odds of a National Trauma Data Standard complication (AOR, 1.20; 95% CI, 1.11-1.30). CONCLUSION: In this large multicenter study, increasing BMI and lower than normal BMI were strongly associated with higher mortality. Increasing BMI was also associated with longer length of stay, increased complications, and unique injury patterns. These untoward outcomes, coupled with a distinct injury pattern, warrant care guidelines specific to trauma patients with higher BMI, as well as those with BMI lower than normal. LEVEL OF EVIDENCE Epidemiological, Level III.