Published Online October 4, 2014
Asthma is a disease with many faces. For years people have tried to subdivide asthma into different phenotypes based on triggers that cause asthma, the course of the disease, or the prognosis. Phenotyping is an important step toward better treatment options and ultimately personalized medicine, as uncontrolled asthma is associated with a high economic burden and impaired quality of life. In order to successfully treat patients with asthma, adequate characterization of the disease is crucial.
In this review by Hekking and Bel, recently published in The Journal of Allergy and Clinical Immunology: In Practice, developing and emerging clinical phenotypes of asthma were described, according to recent literature. In the first part of this review the authors focus on trigger-induced asthma phenotypes such as occupational asthma, cigarette-smoke induced asthma, air pollution-induced asthma and exercise-induced asthma and the potential overlap. The second part gives an overview of asthma phenotypes based on symptoms.
Exacerbation-prone asthma, asthma associated with persistent airflow limitation, cough-variant asthma, asthma with onset in adulthood and the obese asthma phenotype are described. Phenotypes based on biomarkers are discussed in the last part of this review, with the authors focusing on eosinophilic asthma and the role of exhaled nitric oxide and periostin to identify eosinophilic asthma. Furthermore, neutrophilic asthma is described. In a Venn diagram the authors speculate on the possible overlap and relationships between these phenotypes, stratified by childhood versus adulthood onset and by eosinophilic versus non-eosinophilic airway inflammation.
Clinically, recognizing and identifying asthma phenotypes is valuable as it may improve management programs in terms of trigger avoidance strategies or medical treatment approaches. Better understanding of the underlying pathophysiology that differentiates the several phenotypes is needed, although it must be recognized that substantial overlap exists. Collaboration between private and public research entities should support the continual quest to better define phenotypes of asthma.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.