Low Eosinophil Phenotype Predicts Noninvasive Mechanical Ventilation Use in Patients with Hospitalized Exacerbations of COPD

Eosinophilic inflammation is related to the progression and outcomes of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Till now, few studies have focused on low EOS in AECOPD.To reveal the clinical characteristics, therapeutic responses and prognosis of patients hospitalized of AECOPD with low EOS.The electronic database of Zhongshan Hospital, Fudan University was used. Cohort 1 included 608 patients with hospitalized AECOPD. Study population 2 consisted of 166 patients with AECOPD admission at least twice. Impact of low EOS on NIMV treatment, length of hospital stays and 12-month AECOPD-related readmission were analyzed with multivariable logistic regression model. Thirty-five hospitalized AECOPD patients were prospectively recruited as cohort 3 to explore the association between EOS and other immune cells using Spearman correlation coefficient for ranked data.EOS level was suppressed on admission in AECOPD patients, and significantly improved after hospitalized treatment (P < 0.05). For inflammatory markers, leucocytes, neutrophils and lactate dehydrogenase levels were higher, while lymphocytes, monocytes and interleukin-6 levels were lower in the low-EOS group than those in the non-low EOS group (P < 0.05). Low EOS (EOS < 50 cells/μL) was an independent risk factor of NIMV use (OR = 1.86, 95% CI = 1.26 ~ 2.73). The EOS percentage was positively correlated with the T cell percentage (r = 0.46, P < 0.05) and negatively correlated with the natural killer cell percentage (r = -0.39, P < 0.05). The patients with low EOS had lower level of CD4+ T cell (P < 0.05) than that of patients with non-low EOS.Low EOS might be a stable phenotype in patients with hospitalized AECOPD and could be used to inform NIMV management, hyperinflammatory state and impaired immunity situation.