Abstract:

Objective To investigate the relationship between preoperative systemic inflammatory indexes [systemic immune inflammation index（SII），platelet/lymphocyte ratio（PLR），neutrophil/lymphocyte ratio（NLR），lymphocyte/monocyte ratio（LMR）] and infection after internal fixation in patients with open fracture. Methods A total of 398 patients with open fracture treated with internal fixation were enrolled. The general clinical data were collected，and blood routine tests were performed within 24 h before operation. SII，PLR，NLR and LMR were calculated. The patients were followed up for 10 weeks after operation，and they were classified into infection group and non-infection group according to the presence or absence of infection. Kaplan-Meier survival curve was used to analyze the incidence of infection in patients with open fracture. Cox regression analysis was used to evaluate the risk factors of postoperative infection in patients with open fracture. Results In 398 patients with open fracture，41 cases developed postoperative infection. The SII in infection group was higher than that in non-infection group（P=0.002），and there was no statistical significance in PLR，NLR and LMR between the 2 groups（P>0.05）. All the patients were classified into SII≥777 group and SII<777 group according to the median level of SII at baseline. Kaplan-Meier survival curve analysis showed that the postoperative infection rate of SII≥777 group（14.93%） was higher than that of SII<777 group（5.58%）（Log-rankχ²=10.50，P=0.001 2）. After the adjustment for age，sex，body mass index（BMI），diabetes mellitus and hypertension，baseline SII≥777 was an independent risk factor for postoperative infection in open fracture patients [hazard ratio（HR）=3.320，95% confidence interval（CI） 1.450-7.599]. Conclusions Open fracture patients with elevated preoperative SII have a risk of postoperative infection. Preoperative SII has predictive value for postoperative infection in patients with open fracture.

Key words: Systemic immune inflammation index, Platelet/lymphocyte ratio, Neutrophil/lymphocyte ratio, Lymphocyte/monocyte ratio, Open fracture, Infection