Fixed airflow limitation caused by COPD or Asthma: from definition to management

Patients with fixed airflow limitation are often classified as chronic obstructive pulmonary disease (COPD), and some international guidelines recommend classifying asthma with fixed airflow limitation as COPD. Indeed, both COPD (induced by smoking or other noxious agents) and asthma may be associated with a decline of lung function that should cause fixed airflow limitation. In the presence of fixed airflow limitation, patients are often diagnosed COPD, even if the differential diagnosis between asthma and COPD in these patients may be important as the natural history as well as the response to treatment are different, depending on whether fixed airflow limitation is due to asthma or COPD. The assessment of patients presenting with fixed airflow limitation has recently hightlighted that airway inflammation is markedly different in asthma and COPD although characterized by the same degree of airflow limitation. Thus, asthma with fixed airflow limitation maintain the same pathological characteristics as asthma with completely reversible airflow limitation. In conclusion, subjects with asthma have distinct characteristics compared with subjects with COPD. Despite the presence of fixed airflow limitation both patients should be properly identified and treated.