Blood eosinophil as a treatable trait in patients with bronchiectasis

Abstract

Background: Patients with bronchiectasis suffer from a lack of effective treatment to improve dyspnea. However, unfortunately, there is limited information on the treatable trait to improve dyspnoea and lung function in patients with bronchiectasis.

Methods: Using the data from a retrospective cohort of 166 bronchiectasis patients with airflow limitation between January 2005 and February 2015, we identified 156 who had blood eosinophil levels assessed at baseline.

Results: In all patients, FEV1 increased 38 mL after bronchodilator therapy for every 100 (/uL) of eosinophils at baseline (coefficient: 0.38 mL/eosinophil count/uL, 95% CI: 0.14–0.62 mL/eosinophil count/uL). This association was more pronounced in those who used an inhaled corticosteroid (ICS) (coefficient: 0.50 mL/eosinophil count/uL, 95% CI: 0.14–0.89 mL/eosinophil count/uL) than in those who did not (coefficient: 0.19 ml/eosinophil count/uL, 95% CI: -0.09–0.47 mL/eosinophil/uL). We also performed a multivariable linear regression analysis to investigate the impact of eosinophil count on FEV1 change following inhaler use. FEV1 change was only significant among the patients who used ICS (n = 82) (coefficient for change in FEV1: 0.44 mL/eosinophil count/µL; 95% CI, 0.02–0.86 mL/eosinophil count/µL).

Conclusions: Blood eosinophil count was associated with the improvement of lung function in bronchiectasis patients with blood eosinophilia. Adequate ICS use may improve lung function and possibly lead to better treatment outcomes for bronchiectasis patients with eosinophilic phenotype.