Asthma-COPD overlap syndrome and precision medicine.

Differentiation of asthma and chronic obstructive pulmonary disease (COPD) in symptomatic patients has been extremely difficult clinically in many instances. This situation led to the formulation of the so-called “Dutch hypothesis” in 1961,1 cited by Christenson.2 The theory postulates that obstructive lung disease occur in a continuum, with asthma and COPD being expressions of the same disease taking place on the opposite ends of the same spectrum. Although there is no consensus on the definition of asthma-COPD syndrome (ACOS), current understanding would suggest that ACOS is a common clinical and biological manifestation of a separate disease entity with higher morbidity and worse outcomes than COPD or asthma in general with regard to quality of life and increased use of medication. There is hope that clinical variability and biomarkers, such as eosinophilia and type 2 inflammatory markers which are used to identify an ACOS molecular phenotype, would tenably help target therapies for this group of patients. The following information is focused on current evidence on how precision medicine plays a role in the diagnosis of and therapeutics for ACOS. Despite limited understandings of the syndrome, the author proposes precision medicine as a medical application model for identifying individuals by their disease susceptibility, pathobiology, and response to specific treatments. The followings are the possible current practices for this purpose.