Abstract:

Objective

To investigate the relationship between eosinophil （EOS） to neutrophil （NEU）ratio （ENR） and bacterial infection and in-hospital death in patients with acute exacerbation of chronic obstructive pulmonary disease （AECOPD） in intensive care.

Methods

A total of 115 cases AECOPD patients admitted to the intensive care unit （ICU） between January 2020 and January 2024 were selected as study subjects.The percentage of EOS and NEU at admission was measured by blood cell analyzer，and the ratio ENR was calculated.Within 24 hours after admission，all patients underwent laboratory tests，culture tests and PCR to detect pathogen infection status.The primary outcome was survival during hospitalization，and patients were divided into death and survival according to the prognosis.

Results

According to the results of bacterial or viral identification at admission，all the patients were divided into four groups： 30 cases of bacterial infection only，36 cases of viral infection only，21 cases of mixed bacteria-virus infection，and 28 cases of no infection.The ENR （H＝56.407，P＜0.001） and EOS counts （H＝42.010，P＜0.001） were significantly lower in patients with bacterial infection alone or with a combination of bacterial and viral infections.According to ROC curve analysis，ENR had higher identification value for bacterial infection only/bacteria-virus mixed infection，with an AUC value of 0.821 （95%CI： 0.754 ～0.888），which was higher than that of EOS （AUC ＝0.779）.The inhospital mortality rate of ICU patients was 18.26%.Admission ENR was significantly lower in deceased patients compared with survivors ［1.69 （0.45，2.94） vs. 0.21 （0.11，0.33）， Z ＝-5.365， P＜0.001］.Multivariate COX regression analysis revealed that admission ENR was one of the independent risk factors associated with inhospital mortality （HR＝0.179， P ＝0.003）.During the 28-day follow-up period，patients with low ENR had lower survival rates compared with patients with high ENR ［98.25% （56/57） vs.65.52% （38/58）］ and a shorter median survival time （log rank χ² ＝17.376， P＜0.001）.

Conclusion

Low ENR on admission was associated with an increased risk of bacterial infection and 28-day hospitalization death in older AECOPD patients admitted to the ICU.ENR may be an important indicator to evaluate the bacterial infection status and hospitalization prognosis of patients with AECOPD.

Key words: Acute exacerbation of chronic obstructive pulmonary disease, Eosinophil-to-neutrophil ratio, Bacterial infection, Hospitalized death