The association of asthma and atrial fibrillation - A nationwide population-based nested case-control study

Background: Asthmaand atrial fibrillation (AF) have been reported to be related to an increased risk of cardiovascular events. However, the relationship between asthma and AF has not been fully elucidated. The purpose of this study was to examine the association between asthma and AF risk. Methods:Weconducted a population-based nested case-control study including a total of 7439 newly-diagnosed adult patients with AF and 10,075 age-, gender-, comorbidity-, and cohort entry date-matched subjects without AF from the Taiwan National Health Insurance database. Exposure to asthma as well as medications including bronchodilators and corticosteroid before the index date was evaluated to investigate the association between AF and asthma as well as concurrent medications. Results: AF patients were 1.2 times (adjusted OR 1.2, 95% CI 1.109-1.298) more likely to be associated with a future occurrence of asthma independent of comorbidities and treatment with corticosteroids and bronchodilator. In addition, the risks of new-onset AFwere significantly higheramong current users of inhaled corticosteroid, oral corticosteroids, and bronchodilators. Newly users (within 6 months) have the highest risk (inhaled corticosteroid: OR, 2.13; 95% CI, 1.226-3.701, P = 0.007; oral corticosteroid: OR, 1.932; 95% CI, 1.66-2.25, P < 0.001; non-steroid bronchodilator: OR, 2.849; 95% CI, 2.48-3.273, P < 0.001). A graded association with AF risk was also observed among subjects treatedwith corticosteroid (inhaled and systemic administration) and bronchodilators. Newusers (within 6 months) of these medications had the highest risk of AF (ICS: OR, 2.13; 95% CI, 1.226- 3.701, P = 0.007; oral corticosteroid: OR, 1.932; 95% CI, 1.66-2.25, P < 0.001; non-steroid bronchodilator: OR, 2.849; 95% CI, 2.48-3.273, P < 0.001). A graded associationwith AF riskwas also observed among subjects treated with ICS or bronchodilator. Conclusions: Asthma was associated with an increased risk of developing future AF.