Clinical Remission and Its Predictors After 12 Months of Biologic Therapy in Severe Asthma

Background/Objectives: The rates and predictors of clinical remission, a novel and practical therapeutic goal in severe asthma, have been inconsistently reported across studies. Data on clinical remission in Japanese patients remain limited. The aim of this study was to assess the rate of four-component clinical remission and its predictors in Japanese adult patients with severe asthma. Methods: This retrospective study enrolled adult patients with severe asthma who had initiated biologic therapy at least 12 months prior to inclusion at Nagoya City University Hospital. The primary endpoint was the achievement rate of four-component clinical remission, defined as (1) no maintenance oral corticosteroids (OCS); (2) no exacerbations for 12 months; (3) Asthma Control Test (ACT) score ≥ 20; and (4) forced expiratory volume in one second (FEV₁) ≥ 80% of predicted. The secondary endpoint was to identify factors, including airway structural indices measured using chest computed tomography (CT), associated with clinical remission at 12 months. Results: Among 87 patients with severe asthma, 26 (30%) achieved four-component clinical remission after 12 months of biologic therapy. In univariate analysis, clinical remission was more frequently achieved in patients with chronic rhinosinusitis, higher FEV₁ (% predicted), higher blood eosinophil counts, higher ACT scores, fewer exacerbations in the previous year, higher Lund–Mackay scores, and smaller airway wall thickness and luminal areas on CT (all p < 0.05). Multivariate analysis revealed that higher blood eosinophil counts and fewer exacerbations in the previous year were independently associated with clinical remission (both p < 0.05). Conclusions: After 12 months of biologic therapy, 30% of patients with severe asthma achieved four-component clinical remission. Higher blood eosinophil counts and fewer prior exacerbations were associated with higher remission rates.