V.S. Panossian1, I.C. Nzenwa1, V. Van Zon1, M. Bartek1, J. Ng-Kamstra1, M. DeWane1, C.M. Luckhurst1, J.J. Parks1, C. Paranjape1, H.M. Kaafarani1, G.C. Velmahos1, J.O. Hwabejire1 1Massachusetts General Hospital, Division Of Trauma, Emergency Surgery, And Surgical Critical Care, Boston, MA, USA
Introduction: The relationship between body mass index (BMI) and trauma outcomes, often referred to as the "obesity paradox," suggests that a higher BMI might be protective against mortality. This study aims to investigate the association of BMI with outcomes in abdominal trauma.
Methods: The American College of Surgeons Trauma Quality Improvement Program (ACS-TQIP) database 2017-2020 was used for this study. Patients ≥18 years of age with abdominal trauma were included and categorized into six BMI groups: <18.5 kg/m², 18.5-24.9 kg/m², 25-29.9 kg/m², 30-34.9 kg/m², 35-39.9 kg/m², and ≥40 kg/m². The primary outcome of the study was in-hospital mortality. Secondary outcomes were any surgical site infection (SSI): superficial, deep, or organ space SSI, and composite outcome any morbidity, defined as patients developing any of the post-operative complications in ACS-TQIP. Multivariable logistic regression analyses were performed to assess the independent association of each BMI category with outcomes. Sensitivity analyses were performed in patients who underwent an exploratory laparotomy and those with isolated severe abdominal trauma, defined as an Abbreviated Injury Scale (AIS) of 3-5 for the abdomen, excluding patients with extra-abdominal injuries with an AIS greater than 2.
Results: A total of 547,755 patients were included in the study: 4.1% with BMI <18.5 kg/m², 32.9% with BMI 18.5-24.9 kg/m², 31.4% with BMI 25-29.9 kg/m², 17.7% with BMI 30-34.9 kg/m², 7.8% with BMI 35-39.9 kg/m², and 6.1% with BMI ≥40 kg/m². The median age was 43 years, 86.6% had blunt trauma, and 8.6% underwent exploratory laparotomy. The overall mortality rate was 8.3%, morbidity was 8.0%, and the SSI rate was 0.8%. Multivariable logistic regression analyses showed that increased BMI was independently associated with higher rates of mortality, morbidity, and SSI, using a BMI of 18.5-24.9 kg/m² as the reference. On sub-analyses of patients who underwent exploratory laparotomy or had severe isolated abdominal trauma, a similar trend was observed of increasing BMI being associated with worse outcomes when compared to the reference BMI category (Figure 1).
Conclusion: Higher BMI is associated with worse outcomes in abdominal trauma, challenging the notion of the obesity paradox in this patient cohort. Further studies should investigate if the physiology of higher BMI is driving these worse clinical outcomes and whether clinical practices have been adapted to provide appropriate care for this patient cohort.