Morbid Obesity is Not a Risk Factor for Mortality in Critically Ill Trauma Patients

Abstract

Age, Injury severity score (ISS), hyperglycemia (HGL) at admission, and morbid obesity are known risk factors of poor outcome in trauma patients. Our aim was to which risk factors had the highest risk of death in the critically ill trauma patient. A Trauma Registry of the American College of Surgeons database retrospective study was performed at our Level I trauma center from January 2000 to October 2004. Inclusion criteria were age >15 years and >or=3 days hospital stay. Data collected included age, gender, and ISS. Groups were divided into nonobese and morbidly obese (MO) (body mass index, BMI >or=40 kg/m2) and into HGL (mean >or=150 mg/dL on initial hospital day) and non-HGL. Primary outcome was 30-day mortality. Differences in mortality and demographic variables between groups were compared using Fisher's exact and Wilcoxon's rank sum tests. Univariate and multivariate logistic regression was used to assess the relationship of HGL, morbid obesity, age, and injury severity to risk of death. Relationships were assessed using odds ratios (OR) and area under the receiver operator characteristic curve (AUC). A total of 1,334 patients met study criteria and 70.5% were male. Demographic means were age 40.3, ISS 25.7, length of stay 13.4, and BMI 27.5. The most common mechanism of injury was motor vehicle collision 55.1%. Overall mortality was 4.7%. Mortality was higher in HGL versus non-HGL (8.7% vs. 3.5%; p < 0.001). Mortality was higher in MO versus nonobese, but not significantly (7.8 vs. 4.6%; not significant [NS] p = 0.222). Univariate logistic regression relationships of death to age OR: 1.031, p < 0.001, AUC +/- SE: 0.639 +/- 0.042; ISS OR: 1.044, p < 0.001, AUC +/- SE: 0.649 +/- 0.039; HGL OR: 2.765, p < 0.001; MO: OR: NS, p = NS, AUC +/- SE: NS. Relationships were similar in a combined multivariate model. HGL >150 mg/dL on the day of admission is associated with twofold increase in mortality, and an outcome measure should be followed. Morbid obesity (BMI >or=40) is not an independent risk factor for mortality in the critically ill trauma patient.