overlapping of asthma and chronic obstructive pulmonary disease: a literature review

Asthma and chronic obstructive pulmonary disease (copd) are the most common chronic respiratory diseases with significant morbidity in the world. although these diseases have different characteristics, some patients share symptoms and clinical findings of both diseases, socalled asthmacopd overlap syndrome (acos). although there is no gold standard for the diagnosis of acos, it is usually defined as an increased variability of airflow in the respiratory tract. patients with acos are identified with distinct phenotypes such as the increased reversibility of airflow obstruction, eosinophilic bronchial and systemic inflammation, and the increased reaction to inhaled corticosteroids compared to copd patients. the evidence indicates that acos patients are likely to have more dyspnea and cough, more serious symptoms, more hospital admissions, and higher mortality rate. despite these complex conditions, acos patients have been eliminated from clinical trials of asthma and copd and there is little evidence about their clinical decisions. the current study was conducted to review the epidemiology, clinical symptoms, diagnosis, and treatment of acos as the first stage of correct diagnosis and appropriate management of this syndrome in databases such as pubmed, elsevier, google scholar, sid, magiran, google search engine, and so on.