Increased stroke risk among adult asthmatic patients

We conducted a nationwide population-based cohort study to investigate the effects of asthma on the risk of stroke development in an Asian population.

Newly diagnosed asthmatic patients aged ≥ 18 years were identified, and asthma-free controls were randomly selected from the general population and frequency matched according to age, sex and index year using records obtained from the National Health Insurance Research Database between 2000 and 2010. Both cohorts were followed up until the end of 2011 to measure the incidence of stroke. The risk of stroke was analysed using Cox proportional hazard regression models, including factors such as sex, age and comorbidities.

We followed the asthmatic patients for 104 697 person-years and followed the nonasthmatic people for 426 729 person-years. The incidence density rate of stroke increased in all of the groups of asthmatic patients compared with that of the controls when stratified according to sex, age and comorbidities. The hazard ratio (HR) of stroke was 1·37-fold greater for the asthmatic cohort, compared with that for the nonasthmatic cohort, after adjusting for sex, age and comorbidities. The adjusted HR of developing stroke substantially increased with older age and the increased frequency of asthmatic exacerbation and hospitalization. The patients receiving beta-2 agonists as a treatment exhibited a significantly greater risk of stroke compared with the patients receiving only inhaled corticosteroids, after adjusting for covariates.

Asthma may be an independent risk factor for stroke, and its severity exhibits a dose response of stroke development.