Objective: The obesity paradox is the association of increased survival for overweight and obese patients compared to normal and underweight patients, despite an increased risk of morbidity. The obesity paradox has been demonstrated in many disease states but has yet to be studied in trauma. The objective of this study is to elucidate the presence of the obesity paradox in trauma patients by evaluating the association between BMI and outcomes.
Methods: Using the 2014-2015 National Trauma Database (NTDB), adults were categorized by WHO BMI category. Logistic regression was used to assess the odds of mortality associated with each category, adjusting for statistically significant covariables. Length of stay (LOS), ICU LOS and ventilator days were also analyzed, adjusting for statistically significant covariables.
Results: A total of 415,807 patients were identified. Underweight patients had increased odds of mortality (OR 1.378, p < 0.001 95% CI 1.252-1.514), while being overweight had a protective effect (OR 0.916, p = 0.002 95% CI 0.867-0.968). Class I obesity was not associated with increased mortality compared to normal weight (OR 1.013, p = 0.707 95% CI 0.946-1.085). Class II and Class III obesity were associated with increased mortality risk (Class II OR 1.178, p = 0.001 95% CI 1.069-1.299; Class III OR 1.515, p < 0.001 95% CI 1.368-1.677). Hospital and ICU LOS increased with each successive increase in BMI category above normal weight. Obesity was associated with increased ventilator days; Class I obese patients had a 22% increase in ventilator days (IRR 1.217 95% CI 1.171-1.263), and Class III obese patients had a 54% increase (IRR 1.536 95% CI 1.450-1.627).
Conclusion: The obesity paradox exists in trauma patients. Further investigation is needed to elucidate what specific phenotypic aspects confer this benefit and how these can enhance patient care.
Level of evidence: Level III, prognostic study.