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A significant proportion of adult patients over age 40 who present with symptoms of a chronic airways disease have features of both asthma and COPD. Several diagnostic terms, most including the word ‘overlap’, have been applied to such patients, and the topic has been extensively reviewed. However, there is no generally agreed term or defining features for this category of chronic airflow limitation, although a definition based upon consensus has been published for overlap in patients with existing COPD.
This document has been developed by the Science Committees of both GINA and GOLD, based on a detailed review of available literature and consensus. It provides an approach to distinguishing between asthma, COPD and the overlap of asthma and COPD, for which the term Asthma COPD Overlap Syndrome (ACOS) is proposed. Rather than attempting a formal definition of ACOS, this document presents features that identify and characterize ACOS, ascribing equal weight to features of asthma and of COPD. A simple approach to initial treatment of ACOS is also included. It is acknowledged that within this description of ACOS will lie a number of phenotypes that may in due course be identified by more detailed characterization on the basis of clinical, pathophysiological and genetic identifiers. The primary objective of this approach is to inform clinical practice, based on current evidence.