Towards a better phenotyping of chronic obstructive pulmonary diseases.

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality in the world. COPD is defined as a preventable and treatable disease with some significant extrapulmonary effects that may contribute to the severity in individual patients. Its pulmonary component is characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles or gases. COPD is conventionally assessed and monitored by symptoms and physiological measurements, including lung function test before and after inhaled medications. These tests are standardized and used worldwide and they are considered to be the gold standard for the diagnosis and classification of COPD. A limitation of these tests is that they cannot provide relevant information concerning the pathophysiological mechanisms of the disease.