Long-Term Longitudinal Analysis of Pulmonary Function Before and After Biological Therapy in Severe Asthma.

Background: Biological agents are essential treatment options for severe asthma, particularly in cases with Type 2 (T2) inflammation, due to their ability to improve symptoms, prevent exacerbations, and reduce the use of oral corticosteroids. However, limited data exist regarding their long-term effects on lung function, particularly on forced expiratory volume in one second (FEV₁). This study aimed to analyze the longitudinal changes in FEV₁ before and after the initiation of biological agents by following cases over an extended period.

Methods: This study included patients with at least three spirometric measurements before and after the initiation of biological agents, and a follow-up period of at least two years. The primary outcome was the annual change in FEV₁ (ΔFEV₁). Secondary outcomes included comparisons between patients with improved and deteriorated ΔFEV₁, differences based on the type of biological agent used, and comparisons between patients who achieved clinical remission and those who did not.

Results: A total of 41 patients with severe asthma were analyzed. The overall ΔFEV₁ significantly improved after the introduction of biological agents (p < 0.001). Patients with greater declines in FEV₁ prior to treatment showed more pronounced improvements, especially among those treated with anti-IL-5 biologics (mepolizumab and benralizumab) or anti-IL-4 receptor antibodies (p = 0.016 and p = 0.026, respectively). Furthermore, patients with elevated T2 inflammation biomarkers, such as fractional exhaled nitric oxide (FeNO) and peripheral blood eosinophil count (PBE), exhibited greater improvements in FEV₁.

Conclusion: This study indicates that biological agents may help prevent the progressive decline in lung function in severe asthma, particularly among patients with significantly declined lung function or elevated T2 inflammation biomarkers before treatment. Further research is needed to explore differences in efficacy across various biological agents.