[From COPD definitions to COPD phenotypes]

Abstract

COPD is characterized by incompletely reversible airflow limitation (FEV1/FVC < 70%). The historical classification of COPD, which was based on the severity of airflow limitation assessed by the level of FEV1, did not take into account the various aspects of COPD patients. At comparable levels of FEV1, COPD patients show marked heterogeneity in clinical manifestations (dyspnea, rates of exacerbations, exercise capacity, and quality of life), leading to the proposal of the current COPD classification based not only on FEV1, but also on symptoms (dyspnea or quality of life) and history of exacerbations. Limitations of this novel classification of COPD include its relative complexity and the absence of age and comorbidities. Recent identification of clinical COPD phenotypes (i.e., subgroups of COPD patients sharing not only clinical characteristics, but also natural history and/response to therapy) could result in progresses in the pathophysiology of the disease, in the development of specific biomarkers, and could facilitate evaluation of drugs in clinical trials. The development of simple algorithms, using easily available clinical data, will allow identification of phenotypes in clinical practice and may lead to individualized therapies.