The relationship between bronchiectasis and COPD has generated several questions. Is there any real increased prevalence of bronchiectasis in patients with COPD? Does the presence of bronchiectasis have an impact on the clinical characteristics, prognosis, or response to treatment in COPD, to the extent that it can be considered a distinct clinical phenotype? Should bronchiectasis in patients with COPD be seen as merely a comorbidity, or as a consequence of the disease's natural history? Is there a causal relationship between COPD and bronchiectasis? If this is the case, what are the pathophysiological mechanisms responsible for this relationship? And, finally, what is the role of chronic bronchial infection and exacerbations in this relationship?
