The new Global Initiative for Chronic Obstructive Lung Disease update has moved the principles of treatment of stable chronic obstructive pulmonary disease (COPD) forward by including the concepts of symptoms and risks into the decision of therapy. However, no mention of the concept of clinical phenotypes is included. It is recognised that COPD is a very heterogeneous disease and not all patients respond to all drugs available for treatment. The identification of responders to therapies is crucial in chronic diseases to provide the most appropriate treatment and avoid unnecessary medications. The classically defined phenotypes of chronic bronchitis and emphysema, together with the newly described phenotypes of overlap COPD-asthma and frequent exacerbator, allow a simple classification of patients that share clinical characteristics and outcomes and, more importantly, similar responses to existing treatments.These clinical phenotypes can help clinicians identify patients that respond to specific pharmacological interventions. For example, frequent exacerbators are the only subjects with an indication for anti-inflammatory treatment in COPD. Among them, those with chronic bronchitis are the only candidates to receive phosphodiesterase-4 inhibitors. Patients with overlap COPD-asthma phenotype show an enhanced response to inhaled corticosteroids and infrequent exacerbators should only receive bronchodilators. These well-defined clinical phenotypes could potentially be incorporated into treatment guidelines.

The impact of blood eosinophilia in chronic obstructive pulmonary disease (COPD) remains controversial.To evaluate the prevalence and stability of a high level of blood eosinophils (≥300 cells·μL^–1) and its relationship to outcomes, we determined blood eosinophils at baseline and over 2 years in 424 COPD patients (forced expiratory volume in 1 s (FEV₁) 60% predicted) and 67 smokers without COPD from the CHAIN cohort, and in 308 COPD patients (FEV₁60% predicted) in the BODE cohort. We related eosinophil levels to exacerbations and survival using Cox hazard analysis.In COPD patients, 15.8% in the CHAIN cohort and 12.3% in the BODE cohort had persistently elevated blood eosinophils at all three visits. A significant proportion (43.8%) of patients had counts that oscillated above and below the cut-off points, while the rest had persistent eosinophil levels <300 cells·μL^–1. A similar eosinophil blood pattern was observed in controls. Exacerbation rates did not differ in patients with and without eosinophilia. All-cause mortality was lower in patients with high eosinophils compared with those with values <300 cells·μL^–1(15.8%versus33.7%; p=0.026).In patients with COPD, blood eosinophils ≥300 cells·μL^–1persisting over 2 years was not a risk factor for COPD exacerbations. High eosinophil count was associated with better survival.