The Asthma-COPD Overlap Syndrome: A Common Clinical Problem in the Elderly

Figure 6

Common risk factors for the development of obstructive airways disease. Although asthma, COPD, and asthma-COPD overlap syndrome^† likely share many of the same risk factors, it is unknown whether the overlap syndrome is a unique genotype and pathophysiologically unique clinical phenotype. The progression from early life insults to pediatric disease and finally chronic obstructive airway disease in adulthood involves complex genetic, epigenetic, and environmental interactions. Because the underlying pathogenic mechanisms that lead to the overlap syndrome have not be elucidated, we have no known disease-specific therapies other than those extrapolated from clinical trials done in asthma- or COPD-only subjects. In this lies an opportunity for further research focused on the overlap syndrome as the “third arm” of the most common obstructive airway diseases. Given that asthma-COPD overlap syndrome prevalence increases with age, knowledge about this syndrome will have great clinical and economic implications for our aging population. ^†For definitions of the different diagnostic groups, please see the text. Abbreviations: inhaled corticosteroid (ICS), long-acting beta-agonist (LABA), long-acting muscarinic antagonist (LAMA), leukotriene receptor antagonist (LTRA), 5-lipoxygenase (5-LO), body mass index (BMI), airway hyperreactivity (AHR), and lung volume reduction surgery (LVRS).