Exacerbation of respiratory symptoms in COPD patients may not be exacerbations of COPD

To the Editor: Exacerbations of chronic obstructive pulmonary disease (COPD) are defined as acute events characterised by a worsening of the patient's respiratory symptoms, particularly dyspnoea, beyond day-to-day variation, leading to a change in medical treatment and/or hospitalisation 1, 2. Exacerbations of COPD are a leading cause of hospitalisation and healthcare expenditures, particularly in frail, elderly patients. They alter the health-related quality of life and the natural course of disease, increasing the risk of mortality, both during and after the acute event 1, 2. Patients with COPD frequently have chronic comorbidities 1. Several of these comorbidities may produce acute events, contributing to the increased morbidity and mortality in COPD exacerbations: acute myocardial infarction, congestive heart failure, cerebrovascular disease, cardiac arrhythmias and pulmonary circulation disorders 1. By definition, acute exacerbations of COPD are considered respiratory diseases, with specific reference to the respiratory symptoms and to the organs involved (airways and lung). Indeed, respiratory viral or bacterial infections and air pollution are assumed to be the main causes of COPD exacerbations, but the exact contribution of infections is difficult to establish, and the aetiology of a large proportion of exacerbations remains undetermined 1, 3, 4. Although it is known that bronchoconstriction and hyperinflation contribute to the increase in dyspnoea in COPD patients, the chronic airway, pulmonary and systemic inflammation present in patients with stable COPD is associated with an acute …