Asthma and COPD Overlap Syndrome

Different Mechanisms, Similar Outcomes

UC Davis pulmonary specialists and WAF Board Members Samuel Louie and Amir Zeki have named asthma-COPD overlap syndrome, or ACOS.

The physicians recognized the high incidence of the condition — defined by the increased number and intensity of symptoms — after evaluating UC Davis patients with obstructive lung diseases and finding that ACOS was present in about a quarter of patients with severe asthma. They also observed that, on average, 1 in 5 patients with obstructive lung diseases have ACOS.

“It’s standard in our field to diagnose COPD or asthma but not both,” said Louie, professor of internal medicine. “That can lead to treatment plans that don’t fully address the breathing problems of a large group of patients and puts them at risk of losing rather than preserving lung health.”

In articles published in the Journal of Allergy, Expert Reviews in Clinical Pharmacology and Consultant 360, [I’ll create links to the articles] Louie and Zeki presented an diagnosis and treatment approach based on their experiences with patients who have asthma, COPD and ACOS. In May of this year, that approach was incorporated in part by the Global Initiative for Asthma (GINA) and the Global Initiative for Chronic Obstructive Lung Disease (GOLD).

“We don’t have complete consensus yet on the definition of ACOS, given the limited number of studies so far,” said Louie. “But this was a very important start.”

Different mechanisms, similar outcomes

Louie explained that asthma is the result of environmental triggers, including allergens and air pollution, which cause chronic inflammation and airflow obstruction. Adults with COPD have lung damage in the form of emphysema, typically due to smoking or environmental pollution, causing chronic and progressive shortness of breath. A majority of COPD patients also have chronic bronchitis, causing airway swelling, mucus and coughing.

Both diseases lead to acute exacerbations — episodes when breathing rapidly deteriorates, potentially leading to emergency department visits, hospitalizations and death. ACOS patients experience these episodes more frequently and with greater severity than those with asthma or COPD alone.

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