Characteristics and asthma control status in the Korean Severe Asthma Registry-2: a real-world analysis

Background Severe asthma is associated with poor asthma control, leading to poor outcomes. However, few studies have evaluated asthma control status in patients with severe asthma in the biologic era. This study aimed to evaluate baseline asthma control in patients with severe asthma using phase 2 of the Korean Severe Asthma Registry (KoSAR-2). Methods Adult subjects meeting the international consensus definition of severe asthma were prospectively enrolled from 41 hospitals in Korea (March 2022 to June 2023). Data on demographics, comorbidities, lung function, inflammation and healthcare utilisation were collected. Using asthma control test (ACT) scores, patients were classified into a well-controlled asthma group (ACT ⩾20) and poorly controlled asthma group (ACT <20). Results Among 594 severe asthma patients, 51.9% had poorly controlled asthma. Multivariable analysis showed that medical aid (adjusted odds ratio (aOR)=5.515, 95% confidence interval (CI) 2.614–13.110, p<0.001), being underweight (aOR=4.129, 95% CI 1.081–20.192), forced expiratory volume in 1 s <60% predicted (aOR=1.854, 95% CI 1.090–3.175) and prior exacerbations (aOR=3.400, 95% CI 1.987–6.012) were associated with poorly controlled asthma, while T2 inflammation was associated with well-controlled asthma (aOR=0.560, 95% CI 0.316–0.977). However, biologic use was not associated with asthma control status. Conclusions About half of patients with severe asthma in KoSAR-2 had poorly controlled asthma at baseline. While poor socioeconomic status reflected by medical aid was a key factor underlying poor asthma control, T2 inflammation was associated with better asthma control in severe asthma. These findings underscore the importance of both clinical management and socioeconomic support to improve asthma control outcomes.