Asthma is a chronic inflammatory disorder of the airways which causes recurrent episodes of wheezing, breathlessness, chest tightness, and cough, symptoms which are usually associated with reversible airflow limitation.1 ,2 This definition includes the recurrence of respiratory symptoms which might be otherwise classified as asthma exacerbations. However, the term asthma exacerbation is usually reserved for more severe and/or more persistent respiratory symptoms requiring a prolonged increase of current antiasthma medication.1 ,2 Chronic obstructive pulmonary disease (COPD) is defined as a progressive airflow limitation, mostly irreversible.3 ,4 The term COPD includes patients with obstructive chronic bronchitis and/or pulmonary emphysema.3 ,4 Patients with moderate or severe persistent asthma may also have an irreversible component of airflow limitation, and thus they may also be included in the definition of COPD.3 The definition of COPD does not include exacerbations,3-5 even if exacerbations are the main cause of medical intervention and admission to hospital in these patients.