Background: Clinical relevance of cough has been rarely investigated in patients with severe asthma.

Methods: We analyzed the baseline data from the Korean Severe Asthma Registry, a multi-center observational cohort of adult patients with severe asthma in Korea. Cough was evaluated by (1) a physician-diagnosed history of chronic cough (CC) and (2) a patient-reported cough severity visual analogue scale (VAS). The baseline clinical characteristics, disease control status, and medication use were compared according to cough history or severity.

Results: Of the 276 severe asthmatics, 47 (18.1%) had a history of CC. The CC group had significantly higher rates of type 2 inflammation (P = 0.02), allergic comorbidities (rhinitis, conjunctivitis, food allergy and atopic dermatitis, all P < 0.05) and anxiety/depression (P = 0.01), compared to those without CC. Patients with CC had a higher positive rate of bronchodilator responses and a lower rate of fixed airflow obstruction than those without CC (all P < 0.05). Type 2-biologics (P < 0.001) and rescue oral corticosteroid (OCS) were more frequently prescribed (P = 0.03, OR 2.1; 95% CI 1.11-3.99) in patients with CC. The mean cough VAS score was 34.8 ± 28.0 in all subjects. Patients with higher cough scores (VAS ? 50) had worse asthma control and health-related quality-of-life, (all P = 0.05) and more OCS exposure (P < 0.01) than those with lower cough scores (VAS = 0 or 0 < VAS < 50).

Conclusions: Cough may be relevant to important clinical outcomes in patients with severe asthma, particularly OCS use. Further studies are warranted to investigate long-term impact of uncontrolled cough on health outcomes.