Many patients may have bronchial inflammation with features of both asthma and COPD, in a similar way that overlap exists with emphysema and chronic bronchitis. In recognition of this overlap, both GOLD and GINA issued a consensus statement on Asthma, COPD, and Asthma-COPD Overlap Syndrome (ACOS).

ACOS is characterised by persistent airflow limitation with several features usually associated with asthma and several features usually associated with COPD