Asthma as a risk factor for incident stroke in the Atherosclerosis Risk in Communities (ARIC) study

Abstract

Purpose Previous studies found that history of asthma is associated with a higher risk of coronary heart disease in women but not in men. We hypothesized that a history of asthma is also associated with a higher risk of stroke in women. Methods Subjects enrolled in the Atherosclerosis Risk in Communities (ARIC) study, without history of stroke or coronary heart disease at baseline, were classified according to self reported asthma history and age of onset as ever having asthma and ever having either adult onset (onset age ≥21) or childhood onset asthma (onset age Results White blood cell and eosinophil counts were significantly higher in both asthmatic men and asthmatic women compared with their non-asthmatic counterparts. Significantly higher fibrinogen, Factor VIII, Von Willebrand factor, BMI, pack-years of smoking, hypertension, diabetes and a lower level of leisure time physical activity were detected among asthmatic women compared to non-asthmatic women but not among asthmatic men. The crude rate of stroke among women with any history of asthma was 2.25 (95% confidence interval [CI], 1.45 to 3.49) times that of nonasthmatic women. The rate of stroke was increased three-fold in women with adult-onset asthma compared to nonasthmatic women (IDR: 3.07, 95%CI 1.86 to 5.07), while childhood-onset asthma had a weaker and nonsignificant effect (HR: 1.39, 95%CI, 0.62 to 3.14). Men did not experience an increased rate of stroke due to any type of asthma. These associations remained after adjustment for traditional stroke risk factors, physical activity, lung function, and asthma medication use. Conclusion Asthma, particularly adult-onset asthma, is a strong independent risk factor for stroke in women but not in men. Because asthma is a common disease and prevalence is increasing in the United States, it may represent an important emerging risk factor for stroke.