SESSION 9

I think everyone agrees that some patients with asthma may have features of COPD, whereas some patients with COPD may have features normally associated with asthma. The overlap of asthma and COPD has been called a syndrome (ACOS), yet this is misleading as it implies that there is a single disease entity which may require a different therapeutic approach. Both asthma and COPD are common diseases and there is no evidence that development of one may preclude the other, so by chance it would be likely that there will be a coincidence of both diseases, which will appear clinically as a mixture of clinical features of each. Patients with COPD caused by chronic cigarette smoking may have some clinical features of asthma, such as marked airway reversibility and also a response to corticosteroids that may be associated with increased eosinophilia. This may be reflected by increased blood eosinophils (>2% or absolute count of 200/μL). The mechanisms for this blood eosinophilia is not certain but it may or may not reflect airway eosinophilia. The numbers of COPD patients who have features of asthma is approximately 15% in most surveys. Quite different are the patients with asthma who also have features of COPD. These patients include those with increased neutrophils, some of who are smokers but others are non-smokers. These patients tend to have less reversibility and less response to corticosteroids. Some asthmatic patients, especially those with severe persistent asthma, may develop irreversible airway obstruction, thus resembling COPD physiologically but the obstruction is of a different nature to that in COPD (small airway fibrosis) it would be very unusual for these patients to have any evidence of emphysema. Although ACOS does not exist as a distinct syndrome, it is important to recognise the overlap in these diseases as it is important for therapy. COPD patients with asthmatic features are those most likely to benefit for a corticosteroid to reduce exacerbations, whereas those not showing these features should probably not be treated with corticosteroids at all. Asthmatic patients with COPD features may benefit frorn the addition of a long-acting muscarinic antagonist (LAMA) on top of their ICS-LABA combination treatment, Thus both types of overlap should benefit from triple therapy with ICS + LABA + LAMA and these triple cominations are currently in clinical development.