Abstract:Objective: To evaluate peripheral blood cells count［white blood cell (WBC), lymphocyte absolute value, platelet (PLT) ］and their related ratios (i.e. neutrophil to lymphocyte ratio, NLR; lymphocyte to monocyte ratio, LMR; platelet to lymphocyte ratio, PLR; platelet count to mean platelet volume ratio, PLT/MPV) in predicting the severity of respiratory infections in patients with pertussis. Methods: The data of 1 129 patients with pertussis were analyzed retrospectively, and the differences of WBC, PLT, NLR, PLR, LMR and PLT/MPV in peripheral blood were evaluated statistically in different respiratory tract infection groups. Results: A total of 1 129 patients were included in the study. There were statistically significant differences in WBC count levels between the severe pneumonia group and the three non-severe pneumonia groups (the upper respiratory tract infection group, the bronchitis group, and the pneumonia group) (P=0.000, 0.041, 0.000) . The WBC count level in the severe pneumonia group was significantly higher than that in the three non-severe pneumonia groups. The higher the WBC count, the more likely it was to develop severe pneumonia, suggesting that the WBC count of peripheral blood cells can be used as an index to predict severe pneumonia and non-severe pneumonia. There were significant differences in NLR between the severe pneumonia group and the three non-severe pneumonia groups respectively (P=0.000, 0.014, 0.037), between the pneumonia group and the non-pneumonia group (P=0.043) . The NLR of the severe pneumonia group was significantly higher than that of the three non-severe pneumonia groups, and the NLR of the pneumonia group was significantly higher than that of the non-pneumonia group, indicating that the NLR increased with the severity increasing of respiratory tract infection. Especially when severe pneumonia occurred, NLR was significantly higher than the three non-severe pneumonia groups. NLR is an effective index to predict the severity of respiratory tract infection. The higher the NLR, the more severe the respiratory tract infection could be. LMR was statistically higher in the upper respiratory tract infection group than the other three groups (P=0.001, 0.000, 0.001) . The statistics found that the more severe the respiratory tract infection, the lower the LMR, which may be one of the indicators to predict the severity of respiratory tract infection. In addition to the above three indicators, the lymphocytes absolute value, PLT, and PLT/MPV had limited roles in predicting the severity of different respiratory tract infections. Conclusion: WBC and NLR are good independent predictors of severe pneumonia. NLR has a role in predicting pneumonia. The larger the WBC or NLR, the higher the probability of predicting severe pneumonia and the more serious the respiratory infection being.
