E. De La Cruz1, O. A. Olufajo1, A. Zeineddin1, E. Cornwell1 1Howard University College Of Medicine,Surgery,Washington, DC, USA
Introduction:
Obesity is widely acknowledged to be a predictor of increased morbidity and mortality. Multiple studies investigating the association between body mass index (BMI) and blunt abdominal trauma have shown a protective effect of increasing BMI on the severity of injury presumably owing to a “cushion effect”. However, the number of studies exploring the association of BMI and the severity of abdominal penetrating trauma patients is rather limited. The aim of our study is to evaluate that association using a nationwide sample.
Methods:
Data was retrieved from the National Trauma Data Bank (2013-2015). Patients included were those with penetrating abdominal trauma. Patients were stratified by BMI status (<18.5, 18.5-24.9, 25-29.9, 30-39.9, >40). Patients without information on BMI were excluded from the analyses. We defined injury severity using two methods. First, we used the abdomen abbreviated injury scale (AIS) ranging from 1 to 6. Second, we categorized patients as having an abdominal operation vs. no abdominal operation. We evaluated differences in injury severity and mortality across BMI groups using Chi-square tests. Logistic regression multivariate regression models were used to identify independent associations between BMI and the outcomes measured.
Results:
We included 22,110 patients with abdominal penetrating trauma: 10,856 stab wounds, (SW) and 11,254 gunshot wounds (GSW). With increasing BMI, there was a decrease in AIS>2 in SW (26.4%, 27.2%, 26.9%, 23.1%, 20.9%) (P<0.001) and in GSW (60.4%, 51.7%, 52.7%, 50.4%, 48.1%) (P=0.016). The rate of operative management across BMI groups in SW was 43.6%, 43.7%, 43.3%, 44.8%, 46.1% (P<0.655), and in GSW was 59.2%, 58.9%, 59.8%, 60.9%, 54.9% (P=0.084). On multivariate analysis, patients with BMI 30-39.9 had increased odds of undergoing surgical procedures compared to patients with normal BMI [Odds Ratio, OR (95% Confidence Interval, CI)]: 1.15 (1.01-1.30) among those with GSW, but there was no difference in SW. The unadjusted analysis showed an increase in mortality with increasing BMI among patients with GSW (5.8%, 5.9%, 5,2%, 6.9%, 7.8%) (P=0.024), but no difference in mortality with increasing BMI in SW (1.4%, 1.3%, 1.2%, 0.9%, 2.5%) (P= 0.096). However, on multivariate analysis of patients with SW, patients with BMI >40 had increased odds of mortality compared with patients with normal BMI [OR(95% CI): 2.35 (1.08 – 5.06)]. This was also true for patients with BMI >40 among patients with GSW [OR(95% CI): 1.89 (1.26 – 2.86)].
Conclusion:
Increased BMI seems to have a protective effect against penetrating abdominal trauma, as it was associated with lower incidence of severe injury. However, there is increased mortality in morbidly obese patients who were victims of penetrating abdominal trauma. This study suggests that the protective effect of obesity in injury severity may be countered by other factors inherent to the morbidly obese population.