Caracterización clínico-epidemiológica de pacientes con enfermedad pulmonar obstructiva crónica reagudizada Translated title: A clinic and epidemiologic characterization of patients with acute exacerbation of chronic obstructive pulmonary disease

Currently, the diagnosis of chronic obstructive pulmonary disease (COPD) requires a ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC) of less than 0.70 as assessed by spirometry after bronchodilator use. However, many smokers who do not meet this definition have respiratory symptoms.

Airflow obstruction on spirometry is universally used to define chronic obstructive pulmonary disease (COPD), and current or former smokers without airflow obstruction may assume that they are disease free.

Patients with COPD may share some clinical characteristics with asthma sufferers. This phenotypic overlap between COPD and asthma is not yet well characterised. We have analysed data from the EPI-SCAN study, an epidemiological, population-based study in Spain that included 3885 (40 to 80-year-old) subjects in order to investigate the clinical and systemic inflammatory characteristics of COPD patients previously diagnosed with asthma. Generic and COPD-specific quality of life, as well as physical activity, were also assessed through standardised and validated questionnaires. A total of 385 (10.1%) subjects were diagnosed with COPD, 67 (17.4%) being classified with the COPD-asthma overlap phenotype. Such patients were more likely to have dyspnea and wheezing (p<0.001 in both comparisons) and more frequent exacerbations (p<0.001). No differences in systemic inflammatory markers were observed except for lower NOx concentrations in overlap patients (p=0.013). This overlap phenotype significantly worsened specific quality of life (11.1 units on the St. George's Respiratory Questionnaire (SGRQ), 95%CI: 4.88-17.36) and reduced physical activity (3.49 units on the London Chest Activities of Daily Living (LCADL) scale, 95%CI: 1.06-5.94). In this population-based study, 17.4% of the individuals identified with COPD had an overlap COPD-asthma phenotype. This patient subgroup had more dyspnea, wheezing, exacerbations, worse respiratory-specific quality of life, and reduced levels of physical activity. Specific interventions may be required to adequately care for this subgroup of patients. Copyright © 2013 Elsevier Ltd. All rights reserved.