What does phenotype mean in the field of COPD?

Identification of clinical phenotypes in chronic obstructive pulmonary disease (COPD) patients could be useful for associating disease attributes with clinically meaningful outcomes in order to develop more specific treatments that are targeted to various patient subgroups. To have the greatest clinical impact, the definition of a phenotype should be related as strictly as possible to predominant pathogenetic mechanisms of expiratory airflow limitation. To this end, analysis of chest computerized tomography (CT) data has become the reference standard for the investigation of the correlation between the pathologic changes in the airways and parenchyma and other clinical, functional, and chest radiographic data. This in vivo evaluation has been useful in confirming the heterogeneity of the disorder and differentiating patients presenting with very different characteristics. The identification of the two most significant pathogenetic mechanisms of airflow limitation led to the characterization of the two phenotypes: patients with predominant airway obstruction and patients with predominant emphysematous destruction. In spite of the continuing effort with the goal of understanding the various clinical presentations of COPD on the basis of pathogenetic mechanisms and structural changes detected on CT scan, future studies are still needed to aid in developing a reliable model for predicting the phenotype and developing targeted therapeutic interventions. [ABSTRACT FROM AUTHOR]