Factors associated with uncontrolled severe asthma in the biologic era

Background: Despite the development of biologics for severe asthma, individuals with uncontrolled status persist, posing a significant social problem. This multicenter prospective study aimed to identify factors associated with the uncontrolled status of patients with severe asthma in the biologic era assessed using the Asthma Control Questionnaire (ACQ). Methods: Subjects with severe asthma diagnosed by respiratory specialists were enrolled from 11 hospitals. Clinical data and questionnaires were collected. We compared controlled (ACQ-5 <1.5) with uncontrolled severe asthma (ACQ-5 >1.5) and assessed factors linked to uncontrolled severe asthma using logistic regression analysis. Results: One hundred fifty-four patients were analyzed (median age, 66 years; 62.3 % female; 52.6 % administered biologics). Among them, 56 patients (36.4 %) had uncontrolled severe asthma (ACQ-5 >1.5). The uncontrolled group had more frequent exacerbations (>2 times in the previous year) and elevated blood neutrophil counts compared with the controlled group. Factors associated with uncontrolled status were analyzed in the overall population, with patients stratified into two groups: those receiving biologics and those not receiving biologics. Multivariate analysis revealed that frequent exacerbations and elevated blood neutrophil counts were associated with uncontrolled status in the overall population and in patients without biologics, whereas elevated blood neutrophil counts were significantly associated with uncontrolled status in patients receiving biologics. Conclusion: Elevated blood neutrophil counts and frequent exacerbations were independently associated with uncontrolled severe asthma. Specifically, elevated blood neutrophil counts were a significant factor related to uncontrolled status irrespective of biologics, suggesting their potential utility as a biomarker in the biologic era.