title: The impact of body mass index and gender on the development of infectious complications in polytrauma patients.
abstract: OBJECTIVE
  The aim was to test the impact of body mass index (BMI) and gender on infectious complications after polytrauma.
  
  
  METHODS
  A total of 651 patients were included in this retrospective study, with an Injury Severity Score (ISS) ≥16 and age ≥16 years. The sample was subdivided into three groups: BMI <25 kg/m(2), BMI 25-30 kg/m(2), and BMI >30 kg/m(2), and a female and a male group. Infectious complications were observed for 31 days after admission. Data are given as mean ± standard errors of the means. Analysis of variance, Kruskal-Wallis test, χ(2) tests, and Pearson's correlation were used for the analyses and the significance level was set at P < 0.05.
  
  
  RESULTS
  The overall infection rates were 31.0 % in the BMI <25 kg/m(2) group, 29.0 % in the BMI 25-30 kg/m(2) group, and 24.5 % in the BMI >30 kg/m(2) group (P = 0.519). The female patients developed significantly fewer infectious complications than the male patients (26.8 vs. 73.2 %; P < 0.001). The incidence of death was significantly decreased according to the BMI group (8.8 vs. 7.2 vs. 1.5 %; P < 0.0001) and the female population had a significantly lower mortality rate (4.1 vs. 13.4 %; P < 0.0001). Pearson's correlations between the Abbreviated Injury Scale (AIS) score and the corresponding infectious foci were not significant.
  
  
  CONCLUSIONS
  Higher BMI seems to be protective against polytrauma-associated death but not polytrauma-associated infections, and female gender protects against both polytrauma-associated infections and death. Understanding gender-specific immunomodulation could improve the outcome of polytrauma patients.
authors.affiliation: Division of Trauma Surgery, University Hospital Zürich, 8091, Zürich, Switzerland. ladislav.mica@usz.ch.
authors.forename: L
authors.initials: L
authors.lastname: Mica
authors.affiliation: Department of Neurology, University Hospital of Cologne, Cologne, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Keller
authors.affiliation: Department of Thoracic Surgery, University Hospital Brno, Brno, Czech Republic.
authors.forename: J
authors.initials: J
authors.lastname: Vomela
authors.affiliation: Former Head of the Department of Trauma Surgery, University Hospital Zürich, Zürich, Switzerland.
authors.forename: O
authors.initials: O
authors.lastname: Trentz
authors.affiliation: Division of Trauma Surgery, University Hospital Zürich, 8091, Zürich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Plecko
authors.affiliation: University Hospital of Orthopedic Surgery, Inselspital Bern, Bern, Switzerland.
authors.forename: M J
authors.initials: MJ
authors.lastname: Keel
keywords: Body mass index; Gender; ISS; Infection; Polytrauma
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