The overlap syndrome of asthma and chronic obstructive pulmonary disease

7 Asthma and chronic obstructive pulmonary disease (COPD) are both inflammatory respiratory diseases which links the presence of airflow limitation, that is emphasized in their definition. Underlying inflammation demonstrate a qualitatively difference in the prevailing cells and leading inflammatory mediators in each disease. Response to bronchodilators is also generally different in asthma and COPD. Despite these differences, and significant distinctness of the natural course, prognosis and pathogenesis, in clinical practice a proper diagnosis between these two conditions is often difficult to achieve and may be even impossible in some patients due to overlapping features of asthma and COPD in the same patient. Over the years, some patients with asthma becomes irreversible, and many patients with COPD show significant airway hyperreactivity and partially reversible airflow obstruction. Even the profile of inflammation in severe asthma may change similar to that observed in COPD, and exacerbations of COPD proceed with a greater participation of eosinophils. Common risk factors and the fact that asthma itself can increase the likelihood of developing COPD is considered the main reason of coexistence of both diseases (overlap syndrome). Prevalence of the phenomenon forces to develop effective methods of preventing the emergence overlap syndrome, to better differentiate the both diseases, and to search for optimal management strategies and treatment in the cases of their coexistence.