Patients with both type 2 (T2)-high and T2-low severe asthma experience a high disease burden and a high economic burden, which indicates an unmet treatment need, according to findings published in the Journal of Asthma and Allergy.

“Previously, several studies have investigated patients with severe asthma based on their phenotype, particularly T2 inflammatory biomarkers,” the researchers wrote. “The exacerbation risk was found to be higher in [patients with] severe asthma with T2-high features than in those with severe asthma and without any T2-high features. Conversely, other studies did not show a higher exacerbation rate in [patients with] severe asthma with T2-high features. The discrepancy in the results was attributed to the small samples of T2-low [patients with] severe asthma and the inclusion of [patients with] severe asthma treated with biologics, which affected the T2 biomarkers value.”

The investigators aimed to examine characteristics of patients with severe T2-high or T2-low asthma, as well as the disease burden, with patients stratified according to peripheral eosinophil and serum IgE levels. The retrospective cohort study utilized a medical records database of 20 million patients from 160 medical institutions. Patients were aged 17 and older at the index visit, had been treated with an inhaled corticosteroid (ICS) or ICS/long-acting beta agonist (LABA) at least twice during the study baseline, and had available data on eosinophil counts and IgE concentrations.

Comorbidities & Exacerbations Similar in T2-Low & T2-High Groups

Among 732 patients with severe asthma, most (N=599; 81.8%) had T2-high severe asthma. Individuals with T2-high severe asthma were further classified based on eosinophil counts: eosinophil low-IgE high (N=158; 21.6%), eosinophil high-IgE low (N=107; 14.6%), and eosinophil high-IgE high (N=334; 45.6%).

Comorbidities related to allergy included allergic rhinitis, chronic paranasal sinusitis, and atopic dermatitis in the T2-high and T2-low severe asthma populations, all of which were higher in the T2-high group. Patients with T2-high severe asthma also had higher eosinophil and IgE counts.

The researchers observed similar treatment regimens for patients in the T2-high and T2-low groups. Prescriptions included ICS/LABA, short-acting beta agonists, long‐acting muscarinic antagonists, and oral corticosteroids.

The proportion of patients with asthma-related exacerbations, including hospitalization, injectable steroid use, or OCS burst, were 30.6% (95% CI, 26.9% to 34.4%) in the T2-high and 34.6% (95% CI, 26.6% to 43.3%) in the T2-low groups. Specific asthma exacerbations, including hospitalization, injectable steroid use, and OCS burst, were all more common in the T2-low group.

“One of the strengths of this study was the inclusion of a substantial number of [patients with severe asthma] with available data on T2 biomarkers, including eosinophil counts and amount of total IgE,” the researchers wrote. “… These results suggest an unmet treatment need for [patients with] T2-high and T2-low severe asthma.”