Researchers have identified a group of highly symptomatic young asthma patients living in the inner city who have lower allergy and inflammation levels and mildly altered pulmonary physiology, according to a new study.
“Guidelines for managing asthma may not be best suited for this particular group of young asthma sufferers. More study is needed to determine appropriate interventions tailored to this group of children,” said lead author Edward Zoratti, MD, division head of Allergy and Immunology at Henry Ford Health System in Detroit, MI. “It may represent a gap in our understanding of asthma among children experiencing a particular type of the disease.”
Characterizing discrete phenotypes is essential to improving and personalizing asthma care. Zoratti and colleagues designed and conducted the Inner-City Asthma Consortium Asthma Phenotypes in the Inner City study, which included 717 children aged 6 to 17 years.
The researchers collected data at baseline and prospectively every two months for one year. Participants' asthma and rhinitis were optimally managed following guidelines. Cluster analysis was performed in 616 participants completing four or more follow-up visits.
They distinguished five clusters using indicators of asthma and rhinitis severity, pulmonary physiology, allergy (sensitization and total serum IgE), and allergic inflammation.
|- Cluster A was distinguished by lower allergy/inflammation, minimally symptomatic asthma and rhinitis, and normal pulmonary physiology.
- Cluster B had highly symptomatic asthma despite high step-level treatment, lower allergy and inflammation, and mildly altered pulmonary physiology.
- Cluster C had minimally symptomatic asthma and rhinitis, intermediate allergy and inflammation, and mildly impaired pulmonary physiology.
- Clusters D and E exhibited progressively higher asthma and rhinitis symptoms and allergy/inflammation.
- Cluster E had the most symptomatic asthma while receiving high step-level treatment and had the highest total serum IgE level, blood eosinophil count, and allergen sensitizations.
The researchers concluded that allergy distinguishes asthma phenotypes in urban children, with severe asthma often clustering with highly allergic children. However, they also identified a previously unreported cluster with comparatively low allergy and only slightly impaired pulmonary physiology that remained highly symptomatic on high levels of asthma controller therapy.
They suggest that this previously unreported cluster may have uncontrolled or unrecognized comorbidities, such as gastroesophageal reflux disease and rhinosinusitis, that triggered symptoms. Or they may have asthma “masqueraders,” such as vocal cord dysfunction. Also, this cluster had the highest percentage of homes with a resident smoker, so environmental tobacco smoke may have triggered symptoms, such as cough and wheeze, which contributed to symptoms.
“Inner-city children may exhibit unique features of asthma, and phenotypic characterization could be informative of differential responses to asthma management strategies as previously reported in other school-age children and adolescents,” they stated.
“These findings provide a solid basis for personalized care where emphasis on environmental allergen management, allergen desensitization, and anti-TH2 therapy is more appropriate for an allergic phenotype as opposed to the somewhat less-common persistently symptomatic phenotype with little allergy and inflammation that we also identified in this population.”
The researchers published their results in October 2016 The Journal of Allergy and Clinical Immunology.