The association between blood eosinophils and clinical outcome of acute exacerbations of chronic obstructive pulmonary disease: A systematic review and meta-analysis

Studies have shown an association between eosinophilia and clinical outcomes in acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, contradictory findings exist. Our study aims to systematically evaluate the association between elevated peripheral blood eosinophils and clinical outcome of patients with AECOPD. An electronic search was conducted for relevant studies published from database inception to February 28, 2023, on PubMed, EMBASE, Cochrane Library, and Web of Science. The analysis covered studies on the correlation between EOS AECOPD and mortality, hospital stay duration, readmission and hospitalization rates, and invasive mechanical ventilation. Where applicable, relative risk (RR) and weighted mean difference (WMD) were extracted, pooled, and assessed using meta-analysis. Sensitivity analysis was performed to explore the source of heterogeneity. Fifteen high-quality studies including 14 cohort studies and one case-control study were included in the meta-analysis. Compared with non-eosinophilic AECOPD patients, those with eosinophilic AECOPD had a lower risk of mortality (RR = 0.65, 95 % confidence interval [CI] 0.54, 0.77, P