Interaction effect of chronic cough and aging on increased risk of exacerbation in patients with asthma: a prospective cohort study in a real-world setting

Background Elderly individuals with asthma have the greatest burden and worst outcomes, and there is increasing evidence that chronic cough (CC) is associated with asthma severity and poor prognosis. However, clinical characteristics in elderly patients with both asthma and CC have been largely unexplored.

Methods Participants with stable asthma underwent two cough assessments within 3 months to define the presence of CC. Then patients were divided into four groups according to CC and age (≥60 years). Multidimensional assessment was performed at baseline, followed by a 12-month follow-up to investigate asthma exacerbations. Logistic regression models were used to explore the interaction effect of CC and age on asthma control and exacerbations.

Results A total of 310 adult patients were prospectively recruited and divided into four groups: elderly/CC group (n=46), elderly/non-CC group (n=20), younger/CC group (n=112), and younger/non-CC group (n=132). Compared with the younger/non-CC group, the elderly/CC group had worse asthma control, quality of life and increased airflow obstruction. Furthermore, the elderly/CC group had increased moderate-to-severe exacerbations within the 12-month follow-up. In addition, there was a significant interaction effect of chronic cough and aging on the increased moderate-to-severe exacerbations (adjusted risk ratio=2.36; 95% CI, 1.47–3.30).

Conclusion Elderly asthmatics with chronic cough had worse clinical outcomes, including worse asthma control and quality of life, increased airway obstruction, more frequent moderate-to-severe exacerbations, which could be partly explained by interaction effect of chronic cough and aging.