title: The Reemergence of the Asthma-COPD Overlap Syndrome: Characterizing a Syndrome in the Precision Medicine Era.
abstract: OBJECTIVE
  The asthma-COPD overlap syndrome (ACOS) has reemerged in the medical literature. This review addresses our current understanding of ACOS as a clinical and biological entity and how new and existing therapies may be targeted to this group.
  
  
  RESULTS
  Many studies suggest that ACOS is common and associated with more morbidity than asthma and COPD in general. However, there is no consensus on an ACOS definition, likely due to the heterogeneity of the disease. Variable definitions have led to variable results in ACOS studies. Given this clinical variability, biomarkers (e.g., eosinophils and type 2 inflammatory markers) are increasingly being used to identify an ACOS molecular phenotype which appears to be more responsive to inhaled corticosteroids. Although ACOS has become a popular diagnosis, it is unclear whether identifying ACOS as a separate disease entity is clinically useful. Future studies should focus on identifying key clinical features and biomarkers that characterize vulnerable and treatment-responsive patients.
authors: Division of Pulmonary, Critical Care, Allergy, and Sleep Medicine, Department of Medicine, University of California, 513 Parnassus Ave HSE 1355A, San Francisco, CA, 94143, USA. stephanie.christenson@ucsf.edu.
authors: Stephanie A
authors: SA
authors: Christenson
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D057285:Precision Medicine / Q000379:methods*; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000473:pathology
chemical_list: D000305:Adrenal Cortex Hormones
keywords: Asthma-COPD overlap syndrome; Eosinophils; Type 2 inflammation