The impact of body mass index and gender on the development of infectious complications in polytrauma patients

Purpose 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, chi(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. Conclusion 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.