Asthma-COPD Overlap Syndrome (ACOS)


Concept is :
Lung continues to mature through the age of 15-18. Then it plateaus. If any damage occurs to airway and lungs prior to the lung maturation, FEV1 peak that normally occurs would not occur, and they will be 
2 Mechanism of Airflow limitations
  • Small airways disease
  • Parenchymal Destruction (occurs in COPD exclusively
Dynamic Lung Hyperinflation occurs in COPD and not in Asthma. Its a way to differentiate between the two. 
FEV1/FVC decreases with age (age induced emphysema)
While doing PFT, it is reasonable to do with pre and post bronchodilators. Advantage is it helps in the treatment strategy. Note, may not help differentiate Asthma vs COPD fully 

  • Nocturnal Awakening rarely occurs in COPD. It does occur in Asthma or ACOS. 
  • Atopic Disease symptoms are associated with Asthma more than COPD 

Th1 changes to Asthma can lead to COPD, while Th2 changes to COPD patient will lead to Asthma. These will be ACOS. 
Asthma has IgE, produced by Eiosinophils. Hence, likely is mediated by Th2 mediated process. 

Note: Airway reversibility may be absent in patient with ACOS stemming from Asthma. However, Patient with ACOS from COPD may have airway reversibly 

ACOS in summary:
  • Asthma patient no longer has reversible airway obstruction
  • COPD patient now has atopy, reversible airway obstruction, BHR, and wheezing 

Treatment Principles 
  • Treat the nature of inflammation
    • Th2 Type Inflammation - Anti-IL 5 
    • Neutrophil Predominant - Often steroids resident. Note: Steroids will help Neutrophils live longer. 
  • Smoking avoidance or avoid any other trigger
  • Symptomatic Treatment with LABA / LAMA and other medications 
  • Note: Tiotropium is now approved for Asthma.