title: The obesity paradox in surgical intensive care unit patients.
abstract: OBJECTIVE
  To investigate the possible impact of obesity, as assessed by body mass index (BMI), on outcome in surgical intensive care unit (ICU) patients.
  
  
  METHODS
  Prospectively collected data from all consecutive adult patients admitted to our ICU between January 2004 and January 2009 were analysed retrospectively. BMI was calculated using the formula: BMI = body weight/height(2) (kg/m(2)), and patients were grouped as underweight (<18.5 kg/m(2)), normal weight (18.5-24.9 kg/m(2)), overweight (25-29.9 kg/m(2)), obese (30-39.9 kg/m(2)) and very obese (≥40 kg/m(2)).
  
  
  RESULTS
  Among the 12,938 patients who were admitted to our ICU during the study period, 9,935 (76.8%) had complete height and weight data and constituted the study group. The mean BMI was 27.1 ± 5.0 kg/m(2). Overall, 34.4% of the study population had normal BMI, 1.8% were underweight, 41.2% were overweight, 20.8% were obese and 1.8% were very obese. The ICU mortality rate was similar among BMI subgroups, but hospital mortality was higher in underweight patients than in patients with normal BMI (17.8% versus 11.1%, P = 0.006). On multivariate Cox regression analysis, being overweight [hazard ratio (HR) 0.86, 95% confidence interval (CI) 0.74-0.99, P = 0.047] or obese (HR = 0.83, 95% CI = 0.69-0.99, P = 0.047) was independently associated with lower 60-day in-hospital mortality, with normal BMI as the reference category. Risk of death increased in very obese patients, especially after neurosurgical procedures (HR = 0.3, 95% CI = 1.06-8.48, P = 0.039).
  
  
  CONCLUSIONS
  In this cohort of surgical ICU patients, being overweight or obese was associated with decreased risk of 60-day in-hospital mortality.
authors.affiliation: Department of Anaesthesiology and Intensive Care, Friedrich-Schiller-University, Erlanger Allee 103, 07743, Jena, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Hutagalung
authors.forename: Juliana
authors.initials: J
authors.lastname: Marques
authors.forename: Kathrin
authors.initials: K
authors.lastname: Kobylka
authors.forename: Mohamed
authors.initials: M
authors.lastname: Zeidan
authors.forename: Bjorn
authors.initials: B
authors.lastname: Kabisch
authors.forename: Frank
authors.initials: F
authors.lastname: Brunkhorst
authors.forename: Konrad
authors.initials: K
authors.lastname: Reinhart
authors.forename: Yasser
authors.initials: Y
authors.lastname: Sakr
mesh_terms: D000368:Aged; D015992:Body Mass Index; D005260:Female; D005858:Germany / Q000453:epidemiology; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D017063:Outcome Assessment, Health Care; D011183:Postoperative Complications / Q000453:epidemiology*; D011379:Prognosis; D012189:Retrospective Studies