Prognostic Value of the Eosinophil-to-Neutrophil Ratio for In-Hospital Mortality in Patients Hospitalized with Acute Exacerbation of Chronic Obstructive Pulmonary Disease.

Abstract

Inflammatory biomarkers reflecting acute immune responses may aid prognostic stratification in patients hospitalized with acute exacerbation of chronic obstructive pulmonary disease (COPD). The eosinophil-neutrophil ratio (ENR) integrates two key inflammatory cell populations; however, its prognostic value in the acute exacerbation of COPD has not been fully established. We conducted a retrospective cohort study of patients hospitalized for acute exacerbation of COPD between 2016 and 2021. ENR was calculated using peripheral blood eosinophil and neutrophil counts obtained at hospital admission. Patients were categorized into quartiles based on ENR, and outcomes were compared between the lowest quartile (Q1) and the upper three quartiles (Q2-Q4). The primary outcome was in-hospital mortality, and secondary outcomes included all-cause mortality within one year. A total of 435 patients were included (Q1, n=109; Q2-Q4, n=326). The cohort was predominantly male, with a mean age of 74 years. Mean ENR values were significantly lower in Q1 than in Q2-Q4 (0.0002 vs. 0.0471, p<0.001). In-hospital mortality was significantly higher in the Q1 group compared with the Q2-Q4 group (5.5% vs. 1.2%, p=0.019). In multivariable logistic regression analyses, low ENR remained independently associated with an increased in-hospital (adjusted odds ratio, 9.05; 95% confidence interval, 2.19-37.39; p=0.002). ENR was not associated with long-term survival. A low ENR at hospital admission is an independent predictor of in-hospital mortality in patients hospitalized with acute exacerbation of COPD, reflecting heightened acute-phase disease severity.