Overlap of atopic, eosinophilic, and TH2-high asthma phenotypes in a general population with current asthma.

Background: Atopic, eosinophilic, and TH2-high asthma phenotypes may overlap, but the extent is unknown. Understanding the overlap across these phenotypes may be useful in guiding asthma patient care.
Objective: To examine the frequency and overlap of atopic, eosinophilic, and TH2-high asthma phenotypes.
Methods: We analyzed 2005 to 2006 data from the National Health and Nutrition Examination Survey. Patients with asthma were identified based on the participant self-report. Eosinophilic asthma was defined as a blood eosinophil cutoff point of ≥150, 300, or 400/μL. Atopic asthma was defined as having an allergen-specific IgE level of ≥0.35 IU/mL for any of the 9 perennial allergens tested. TH2-high asthma was defined as a total serum IgE of ≥100 IU/mL and a blood eosinophil count of ≥140/μL.
Results: The study included 269 children and 310 adults. Depending on the eosinophil cutoff used, 31% to 78% of children and 21% to 69% of adults with asthma were classified as having eosinophilic asthma. In addition, 63% of children and 61% of adults were classified as having atopic disease and 48% of children and 37% of adults as having TH2-high asthma. At a higher eosinophil cutoff point, a greater proportion of eosinophilic asthma can be classified as atopic or TH2 high, but a lower proportion of atopic or TH2-high asthma can be classified as eosinophilic. Approximately 70% or more of children and adults with asthma were 1 of these 3 phenotypes.
Conclusion: A considerable overlap among eosinophilic, atopic, and TH2-high asthma phenotypes exists in a general asthma population.
(Copyright © 2016 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)