Chronic obstructive pulmonary disease (COPD) is a heterogeneous disorder encompassing different phenotypes with different responses to treatment. The present 1-year, two-center hospital-based study investigated whether the plasma immunoglobulin E (IgE) level and/or eosinophil cell count could be used as biomarkers to stratify patients with COPD according to predicted responses to inhaled corticosteroids (ICS)-based therapy.
A hospital-data based cohort study of COPD patients treated at two territory hospital centers was conducted for 1 year. Allergic biomarkers, including blood eosinophil counts and IgE levels, were assessed at baseline. Lung function parameters, including forced expiratory volume in 1 second (FEV 1), forced vital capacity (FVC), and the COPD Assessment Test (CAT), were also evaluated. The frequencies of acute exacerbation (AE) and pneumonia were also measured. Eosinophilia and a high IgE level were defined as >3% and 173 IU/mL, respectively.
A total of 304 patients were included. Among patients with eosinophilia and high IgE levels, ICS-based therapy was associated with significant improvements in FEV 1, FVC, and CAT scores, compared with bronchodilator (BD) therapy ( P≤0.042). ICS-based therapy was also associated with a significantly lower incidence of AE vs BD-based therapy (11.7% vs 24.1%; P<0.008). Among patients with only eosinophilia, ICS-based therapy yielded significantly better CAT score results vs BD-based treatment (7 vs 13; P=0.032). A receiver operating characteristic curve analysis found that the combination of a high plasma IgE level and eosinophilia most sensitively and specifically identified patients who would benefit from the addition of ICS to BD therapy.