PURPOSE OF THE STUDY.
The goal of this study was to identify wheezing and asthma phenotypes based on the time course of respiratory/allergic symptoms throughout preschool years.
A total of 3840 term healthy infants born between 2003 and 2006 were enrolled in a population-based birth cohort study (PARIS). Of the 3840 children initially enrolled in the cohort, 2522 children were included in the cluster analysis.
Data (including symptoms of wheezing, dry night cough, rhinitis, and dermatitis) were collected annually from birth to 4 years of age. K-means clustering was used to group, into phenotypes, children with similar symptom trajectories over the study period. Children with complete reports for all symptoms at all time periods underwent a sensitivity analysis. Once respiratory/allergic phenotypes were identified, their relations with IgE-mediated sensitization, blood eosinophilia, and physician-diagnosed disease were studied by using logistic regression. The risk factors for belonging to these phenotypes were investigated by using multinomial logistic regression.
Four distinct respiratory/allergic phenotypes and 1 reference group were identified. The 4 phenotypes included 2 transient (rhinitis and wheeze) and 2 persistent ones that were associated with IgE sensitization (cough/rhinitis phenotype and dermatitis phenotype). Early lower respiratory tract infections were far more prevalent among the transient wheeze phenotype. The transient rhinitis phenotype never statistically differed from the reference group nor did the transient wheeze phenotype except for diagnosed asthma. The dermatitis phenotype had the highest prevalence of diagnosed eczema and food allergy. The cough/rhinitis phenotype showed the highest prevalence of diagnosed asthma and hay fever, which statistically differed from all the other phenotypes. The only factor associated with the transient rhinitis phenotype was postnatal exposure to environmental tobacco smoke in the home. Transient wheeze phenotype was related to male gender and contact with other children. Lastly, risk factors for both IgE-associated phenotypes encompassed parental history of allergy and potential exposure to stress and allergens, known to be associated with the development of allergic disease.
This study identified 4 distinct phenotypes based on the time course of respiratory/allergic symptoms in the first 4 years of life. The different phenotypes varied in terms of IgE sensitization and risk factors. The transient phenotypes were linked to irritation and infections, and the persistent phenotypes to allergy.
This study reaches results similar to previously published studies, categorizing children into different clinical phenotypes and groups at risk for developing asthma. Most children with transient wheeze will not go on to develop asthma. In contrast, the persistent cough/rhinitis phenotype associated with IgE sensitization predicted the highest prevalence of diagnosed asthma. Thus, children with risk factors (mainly parental history of allergy), dry night cough, and/or rhinitis not associated with infection should be referred to an allergist early on for allergy testing. Identification of IgE sensitization should change management in a child with a higher risk of developing asthma.
- Copyright © 2014 by the American Academy of Pediatrics