title: Adverse respiratory effect of acute β-blocker exposure in asthma: a systematic review and meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  β-Blockers are avoided in asthma over concerns regarding acute bronchoconstriction. Risk is greatest following acute exposure, including the potential for antagonism of β2-agonist rescue therapy.
  
  
  METHODS
  A systematic review of databases was performed to identify all randomized, blinded, placebo-controlled clinical trials evaluating acute β-blocker exposure in asthma. Effect estimates for changes in respiratory function, symptoms, and β2-agonist response were pooled using random effects meta-analysis with heterogeneity investigated.
  
  
  RESULTS
  Acute selective β-blockers in the doses given caused a mean change in FEV1 of −6.9% (95% CI, −8.5 to −5.2), a fall in FEV1 of ≥20% in one in eight patients (P=.03), symptoms affecting one in 33 patients (P=.18), and attenuation of concomitant β2-agonist response of −10.2% (95% CI, −14.0 to −6.4). Corresponding values for acute nonselective β-blockers in the doses given were −10.2% (95% CI, −14.7 to −5.6), one in nine patients (P=.02), one in 13 patients (P=.14), and −20.0% (95% CI, −29.4 to −10.7). Following investigation of heterogeneity, clear differences were found for celiprolol and labetalol. A dose-response relationship was demonstrated for selective β-blockers.
  
  
  CONCLUSIONS
  Selective β-blockers are better tolerated but not completely risk-free. Risk from acute exposure may be mitigated using the smallest dose possible and β-blockers with greater β1-selectivity. β-Blocker-induced bronchospasm responded partially to β2-agonists in the doses given with response blunted more by nonselective β-blockers than selective β-blockers. Use of β-blockers in asthma could possibly be based upon a risk assessment on an individual patient basis.
authors.affiliation: Quality, Safety, and Informatics Group, Medical Research Institute, University of Dundee, Dundee. Electronic address: danielmorales@nhs.net.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Morales
authors.affiliation: Bute Medical School, University of St Andrews, Fife, Scotland.
authors.forename: Cathy
authors.initials: C
authors.lastname: Jackson
authors.affiliation: Asthma and Allergy Research Group, Medical Research Institute, University of Dundee, Dundee.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Lipworth
authors.affiliation: Dundee Epidemiology and Biostatistics Unit, Medical Research Institute, University of Dundee, Dundee.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Donnan
authors.affiliation: Quality, Safety, and Informatics Group, Medical Research Institute, University of Dundee, Dundee.
authors.forename: Bruce
authors.initials: B
authors.lastname: Guthrie
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000009:adverse effects*; D001249:Asthma / Q000188:drug therapy* / Q000503:physiopathology*; D005541:Forced Expiratory Volume / Q000187:drug effects*; D006801:Humans; D016032:Randomized Controlled Trials as Topic
chemical_list: D000319:Adrenergic beta-Antagonists