Abstract: Objective To analyze the correlation and interaction between peripheral blood neutrophil/lymphocyte ratio (NLR),Creactive protein (CRP)/albumin (ALB) and postoperative pulmonary infection in patients with traumatic brain injury (TBI). Methods A total of 210 TBI patients were selected from March 2022 to October 2024 in Red Cross Hospital Affiliated to Xi'an Jiaotong University.According to whether pulmonary infection occurred during postoperative hospitalization,they were divided into an infected group (nP=73) and a noninfected group (nP=137).The general data,preoperative peripheral blood NLR and CRP/ALB levels were compared between the two groups.The influencing factors of pulmonary infection after TBI were analyzed.The predictive value of preoperative peripheral blood NLR and CRP/ALB on pulmonary infection after TBI was analyzed.The conventional Logistic model was constructed according to the conventional influencing factors.The new Logistic model was constructed according to the conventional influencing factors and preoperative peripheral blood NLR and CRP/ALB.The value of the two models in predicting pulmonary infection after TBI was compared. Results The proportion of diabetes mellitus,preoperative serum procalcitonin (PCT),interleukin-6 (IL-6),peripheral blood NLR and CRP/ALB levels in the infected group were higher than those in the uninfected group,and the preoperative Glasgow Coma Scale (GCS) score was lower than that in the uninfected group (P<0.05).Diabetes mellitus,preoperative serum PCT,IL-6,peripheral blood NLR,CRP/ALB were independent risk factors for pulmonary infection after TBI,and preoperative GCS score was an independent protective factor (P<0.05).The area under the curve (AUC) of preoperative peripheral blood NLR and CRP/ALB in predicting pulmonary infection after TBI was 0.728 and 0.719,respectively (P<0.05).The AUC of conventional Logistic model and new Logistic model in predicting pulmonary infection after TBI were 0.827 and 0.912,respectively (P<0.05).Compared with the conventional Logistic model,the AUC of the new Logistic model in predicting pulmonary infection after TBI was significantly increased (P<0.05). Conclusion The increase of preoperative peripheral blood NLR and CRP/ALB levels can increase the risk of pulmonary infection after TBI.The establishment of a new Logistic model based on preoperative peripheral blood NLR and CRP/ALB can improve the predictive value of pulmonary infection after TBI.

Key words: traumatic brain injury; pulmonary infection; neutrophil lymphocyte ratio; C-reactive protein/albumin; correlation; interaction