Obesity as a Risk Factor for Nosocomial Infections in Trauma Patients

BACKGROUND: Obesity, like multiple trauma, is associated with an inflammatory condition that leads to an immunodeficient state. Obese trauma patients are thus thought to he at higher risk of infection compared to patients of normal body mass. Despite this risk, studies to date have not defined obesity as an independent risk factor for infection in trauma patients. STUDY DESIGN: Retrospective data were collected on 1,024 patients admitted to a Level I trauma center during a 12-month period. Obesity was defined as a body mass index (BMI) >= 30 kg/m(2). Outcomes analyzed included urinary tract infection, pneumonia, septicemia, and wound infection and Clostridium difficile infection. Multiple logistic regression was used to evaluate the contribution of each BMI category to infection while adjusting for comorbidities, age, gender, Injury Severity Score (ISS), hospital and ICU lengths of stay, and number of ventilator days. RESULTS: Obesity prevalence was 30.6%. Obese patients had longer hospital length of stay, with similar ISS, number of ventilator days, and ICU length of stay. The overall rate of infections was 8.7%. Variables independently associated with increased risk of infections were BMI, age, ISS, ICU length of stay, hospital length of stay, and multiple comorbidities. The risks of infections according to each BMI category were: BMI <= 25 kg/m(2), 4.2%, BMI 25 to 29 kg/m(2), 9.5%, odds ratio (OR) 2.65 (CI 0.72 to 5.72); BMI 30 to 39 kg/m(2), 12%, OR 4.69 (CI 2.18 to 10.08); and BMI >= 40 kg/m(2), 20.3%, OR 5.91 (Cl 2.18 to 16.01). Pulmonary and wound infections were significantly more frequent in obese patients. CONCLUSIONS: In this retrospective study, obesity was shown to be an independent risk factor for nosocomial infection after trauma. Prospective studies would clarify the reasons associated with this increased risk of infections in obese trauma patients. (J Am Coll Surg 2010;211:61-67. (C) 2010 by the American College of Surgeons)