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

RATIONALE: 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. OBJECTIVE: To reveal the clinical characteristics, therapeutic responses and prognosis of patients hospitalized of AECOPD with low EOS. METHODS: 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. RESULTS: 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. CONCLUSION: 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.