COPD and bronchiectasis – a real phenotype?

Abstract

Bronchiectasis is an anatomical diagnosis, arising from a diverse range of mechanisms conceptualised as a 'vicious cycle' and ultimately resulting in permanently dilated airways. COPD is a physiological diagnosis – the end result of a susceptible individual being exposed to sufficient airborne environmental toxin. Confusion between COPD and bronchiectasis arises because of the potential for a similar clinical presentation. However, when extensive, bronchiectasis can result in fixed airflow obstruction that meets the physiological definition for COPD and conversely, some patients with COPD have airway wall changes – typically airway wall thickening rather than dilation – which is commonly labelled as 'bronchiectasis'. Cue confusion, and talk of 'BCOS' – a bronchiectasis-COPD overlap syndrome. Whether you accept this or not, it is important to note that fixed airflow obstruction is associated with poor outcomes in bronchiectasis (FEV1 is a component of BSI and FACED), and airway wall changes have been associated with poor outcomes in COPD. Therapy differs significantly between COPD and bronchiectasis: this presentation will therefore argue that it IS important to distinguish the primary pathology.