Use of β-blockers and the risk of asthma exacerbations

Background: β-blockers are contra-indicated in asthma because of potential bronchoconstriction. There is emerging evidence that β-blockers are safe in asthmatics with cardiovascular comorbidity. Objectives: To study the association between β-blocker use and the risk of moderate to severe asthma exacerbations (AE). Methods: We conducted 2 case-control (CC) studies, nested in an asthma cohort within the Dutch IPCI medical record database. Study period was from 2008-2013. Cases were asthma patients (u003e18 yrs) with a first severe AE requiring hospitalisation/ED visit (first CC set). In the 2nd CC set, cases had a first AE requiring systemic corticosteroids or hospitalisation/ED visit. To each case, controls were matched on age, gender, GP practice and index date. β-blocker use was categorized by type (cardioselective vs. non-cardioselective) and categorized into no, current or past use. Effect of duration and dose was investigated. Conditional logistic regression analysis was used. Results: In the first CC set, 1,454 cases (mean age 49 yrs, 70% females), were matched to 11,199 controls. Current use of β-blockers was not associated with an increased risk of AE (OR adj 0.8, 95%CI 0.6-1.0). No association was observed by type of β-blocker nor by dose. In the second CC set, 10,934 cases were matched to 74,415 controls (mean age 54 yrs, 67% females). Also in this 2nd set, there was no association between current use and the risk of moderate to severe AEs (OR adj 0.9, 95%CI 0.8-1.0). No effect modification by COPD was observed. Conclusions: Our study did not show an increased risk of moderate to severe asthma exacerbations and β-blocker use. These findings might be confounded by contra-indication and warrant further research.