AB028. Use of β-blockers and the risk of asthma exacerbations

Background: Asthma guidelines list asthma as a contraindication to β-blocker use because of the potential of bronchoconstriction. Contrary to this assumption, there is emerging evidence that treatment with β-blockers might be safe and well tolerated in patients with asthma, especially in those with underlying cardiovascular comorbidity. To study risk factors of asthma exacerbations and to study the association between the use of β-blockers (in patients with asthma) and the risk of moderate to severe asthma exacerbations.

Methods: We conducted 2 observational case-control studies, nested in a cohort of asthma patients within the Dutch Integrated Primary Care Information (IPCI) medical record database. The study period was from 2008 to 2013. Cases were asthma patients (>18 years old) with a first severe asthma exacerbation requiring hospitalisation/ED visit (first case-control set). In the second case-control set, cases were asthma patients with an asthma exacerbation requiring systemic corticosteroids or hospitalisation/ED visit. To each case, all eligible asthmatic controls were matched on age, gender, GP practice and index date. Exposure to β-blockers was categorized by type of β-blocker (cardioselective vs. non-cardioselective) and categorized into no use, current or past use. Effect of duration of use and dose of β-blocker was investigated. Data were analyzed using conditional logistic regression analysis.

Results: In the first case-control set, 1,454 patients (mean age 49 yrs, 70% females), requiring hospitalization or ED visit due to an asthma attack were matched to 11,199 controls. Current use of β-blockers was not associated with an increased risk of asthma exacerbations (ORadj 0.8; 95% CI, 0.6–1.0). No association was observed by type of β-blocker (non-cardioselective versus cardioselective) and no dose effect relationship was observed. In the second case set, 10,934 cases with an asthma exacerbations consisting of either hospitalization, ED visit or use of systemic corticosteroids were matched to 74,415 controls (mean age 54 yrs, 67% females). Also in this second case-control set, there was no association between current use of β-blockers and the risk of moderate to severe asthma exacerbations (ORadj 0.9; 95% CI, 0.8–1.0).

Conclusions: Our study did not show an increased risk of moderate to severe exacerbations in asthma patients treated with β-blockers. However, these observational findings might be influenced by confounding by contra-indication, and should thus be interpreted with caution.

Keywords: β-Blockers; asthma; asthma exacerbations; contra-indication