Blood eosinophil count and pneumonia risk in patients with chronic obstructive pulmonary disease: a patient-level meta-analysis

Inhaled corticosteroids are important in the management of chronic obstructive pulmonary disease (COPD), but can slightly increase the risk of pneumonia in patients with moderate-to-severe COPD. Patients with circulating eosinophil counts of 2% or more of blood leucocytes respond better to inhaled corticosteroids than do those with counts of less than 2% and it was therefore postulated that blood eosinophil count might also have an effect on the risk of pneumonia in patients with COPD. In this post-hoc meta-analysis, we investigate whether a 2% threshold can identify patients who differ in their risk of pneumonia, irrespective of inhaled corticosteroid treatment.From the GlaxoSmithKline trial registry, we selected randomised, double-blind, clinical trials of patients with COPD that had: inhaled corticosteroid arms (fluticasone propionate and salmeterol or fluticasone furoate and vilanterol); a control arm (not given inhaled fluticasone); and pre-randomisation measurements of blood eosinophil counts and were of at least 24 weeks in duration. With use of specified terms from the Medical Dictionary for Regulatory Activities we identified pneumonia adverse events in patient-level data. We calculated number of patients with pneumonia events, stratified by baseline blood eosinophil count (