PURPOSE: Multiple factors contribute to morbidity and mortality in acutely ill patients requiring intensive care monitoring. Pre-hospitalization factors, chronic conditions, acuity of presentation and progression of disease, have been incorporated into survival predictive models. Body mass index (BMI) is not used in these models as a possible risk factor. We compare the relationship between BMI on hospital mortality of surgical ICU patients.
METHODS: We analyzed 1860 patients, admitted to our institution’s surgical intensive care unit (SICU). Patients who did not undergo surgery and patients under the age of 18, were excluded from the analysis. The effect of BMI on mortality was assessed using the area under the receiver operating characteristic curves (AUC). The data were further stratified to discriminate the effect of BMI on groups with pre-determined risk factors; age and type of admission (elective vs. emergency surgery)
RESULTS: Thirty day hospital mortality was 10.3%. The hospital mortality for under weight patients (BMI<20), normal weight (BMI 20-25), overweight (BMI 25-30), obese (BMI 30-35), severely obese (BMI 35-50), and super-obese (BMI> 50) were 15.0%, 10.7%, 8.2%, 9.0%, 12.9%, 22.2% respectively. The comparison between the different weight groups did not yield statistical significance. There was no association between the BMI and mortality as demonstrated by the area under the receiver operating characteristic curve (AUROCC), 0.48. The relationship between BMI and mortality was further examined by calculating the AUROCC after stratifying patients in elective surgery, emergency surgery, patients younger and older than 75 years of age, which consistently showed no association, with values ranging from 0.46 to 0.53.
CONCLUSIONS: At our institution, there was a trend towards increased mortality for underweight, obese, and severely obese patients, which was not statistically significant when compared to patients of normal weight. There was no association between mortality and BMI.
CLINICAL IMPLICATIONS: BMI is not an independent factor associated with hospital mortality for patients admitted to the surgical ICU.
DISCLOSURE: The following authors have nothing to disclose: Adam Khader, Garry Ritter, Rajeev Gupta, Denis Knobel, Gary Deutsch, Corrado Marini, Rafael Barrera
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