title: The impact of BMI on polytrauma outcome.
abstract: BACKGROUND
  Varying results have been reported concerning the effect of body mass index (BMI) on polytrauma outcome. Although most studies focus on obesity and its associated preexisting medical diseases as a predictor for increased mortality rates, there is evidence that polytrauma patients with underweight also face an inferior outcome.
  
  
  METHODS
  Records of 5766 trauma patients (minimum 18 years of age, Injury Severity Score ≥ 16, treated from 2004 to 2008) documented in the Trauma Registry of the German Society for Trauma Surgery were subclassified into 4 BMI groups and analysed to assess the impact of BMI on polytrauma outcome.
  
  
  RESULTS
  Underweight (BMI Group I) as well as obesity (BMI Group IV) in polytraumatized patients are associated with significantly increased mortality by multivariate logistic regression analysis with hospital mortality as the target variable (adjusted odds ratio for BMI Group I, 2.1 (95% CI 1.2-3.8, p = 0.015); for BMI Group IV, 1.6 (95% CI 1.1-2.3, p = 0.009)). Simple overweight (BMI Group III) does not qualify as a predictor for increased mortality (odds ratio 1.0; 95% CI 0.8-1.3).
  
  
  CONCLUSIONS
  There is a significant correlation between obesity, underweight, and increased mortality in polytraumatized patients. Efforts to promote optimal body weight may reduce not only the risk of chronic diseases but also the risk of polytrauma mortality amongst obese and underweight individuals.
authors.affiliation: Department of Trauma, Hand- and Reconstructive Surgery, University Hospital Hamburg Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany. mihoffma@uke.uni-hamburg.de
authors.forename: Michael
authors.initials: M
authors.lastname: Hoffmann
authors.forename: Rolf
authors.initials: R
authors.lastname: Lefering
authors.forename: Michaela
authors.initials: M
authors.lastname: Gruber-Rathmann
authors.forename: Johannes Maria
authors.initials: JM
authors.lastname: Rueger
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lehmann
mesh_terms: D000328:Adult; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D017052:Hospital Mortality / Q000639:trends; D006801:Humans; D015601:Injury Severity Score; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009104:Multiple Trauma / Q000401:mortality* / Q000503:physiopathology / Q000601:surgery*; D015999:Multivariate Analysis; D009765:Obesity / Q000150:complications* / Q000401:mortality / Q000503:physiopathology; D016017:Odds Ratio; D012189:Retrospective Studies; D012307:Risk Factors; D013851:Thinness / Q000150:complications* / Q000401:mortality / Q000503:physiopathology; D016896:Treatment Outcome; D014945:Wound Healing