Causes of death in patients with asthma and asthma-chronic obstructive pulmonary disease overlap syndrome.

The administration of inhaled corticosteroids and worldwide usage of several asthma guidelines have improved asthma mortality. Elderly patients with asthma show high mortality rates, and may have several comorbidities, including overlap with chronic obstructive pulmonary disease (COPD). Among patients showing asthma overlapped with COPD (asthma-COPD overlap syndrome; ACOS), mortality is worse than for asthma alone. Therefore, we investigated comorbidities, malignancies, and causes of death in patients with asthma and ACOS.