Bronchiectasis phenotypes.

Bronchiectasis is a chronic respiratory disease with heterogeneous clinical manifestations and outcomes. Identifying clinical phenotypes could help in managing bronchiectasis patients and hopefully improve disease prognosis by adopting personalized treatment. We review the current literature on clinical phenotypes of bronchiectasis and try to highlight priorities for future research. Different studies have tried to stratify bronchiectasis patients according to cause, microbiology, or associated conditions. In consideration of the huge heterogeneity of bronchiectasis different cluster analyses in bronchiectasis have also been performed. Unfortunately classification by cause is clinically meaningful only in a few conditions in which specific treatment is available or a specific management is recommended. This is the case, for instance, of allergic bronchopulmonary aspergillosis, immunodeficiencies or chronic airways comorbidities of bronchiectasis, such as chronic obstructive pulmonary disease and asthma. From a clinical perspective, the microbiological cluster stratification proposed by Aliberti et al. seems the most profitable one but still so a number of host-related factors have an unpredictable effect on clinical manifestations and outcomes of bronchiectasis. Although numerous attempts to identify clinical phenotypes in bronchiectasis have been performed, currently there is need to further investigate the host-related factors (endotypes) that surely play a determinant role in disease severity.