title: Meta-analysis: anticholinergics, but not beta-agonists, reduce severe exacerbations and respiratory mortality in COPD.
abstract: BACKGROUND
  Anticholinergics and beta2-agonists have generally been considered equivalent choices for bronchodilation in chronic obstructive pulmonary disease (COPD).
  
  
  OBJECTIVE
  To assess the safety and efficacy of anticholinergics and beta2-agonists in COPD.
  
  
  METHODS
  We comprehensively searched electronic databases from 1966 to December 2005, clinical trial websites, and references from selected reviews. We included randomized controlled trials of at least 3 months duration that evaluated anticholinergic or beta2-agonist use compared with placebo or each other in patients with COPD.
  
  
  METHODS
  We evaluated the relative risk (RR) of exacerbations requiring withdrawal from the trial, severe exacerbations requiring hospitalization, and deaths attributed to a lower respiratory event.
  
  
  RESULTS
  Pooled results from 22 trials with 15,276 participants found that anticholinergic use significantly reduced severe exacerbations (RR 0.67, confidence interval [CI] 0.53 to 0.86) and respiratory deaths (RR 0.27, CI 0.09 to 0.81) compared with placebo. Beta2-agonist use did not affect severe exacerbations (RR 1.08, CI 0.61 to 1.95) but resulted in a significantly increased rate of respiratory deaths (RR 2.47, CI 1.12 to 5.45) compared with placebo. There was a 2-fold increased risk for severe exacerbations associated with beta2-agonists compared with anticholinergics (RR 1.95, CI 1.39 to 2.93). The addition of beta2-agonist to anticholinergic use did not improve any clinical outcomes.
  
  
  CONCLUSIONS
  Inhaled anticholinergics significantly reduced severe exacerbations and respiratory deaths in patients with COPD, while beta2-agonists were associated with an increased risk for respiratory deaths. This suggests that anticholinergics should be the bronchodilator of choice in patients with COPD, and beta2-agonists may be associated with worsening of disease control.
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. salpeter@stanford.edu
authors.forename: Shelley R
authors.initials: SR
authors.lastname: Salpeter
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Buckley
authors.forename: Edwin E
authors.initials: EE
authors.lastname: Salpeter
mesh_terms: D000318:Adrenergic beta-Agonists / Q000627:therapeutic use*; D018680:Cholinergic Antagonists / Q000627:therapeutic use*; D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000401:mortality*; D016032:Randomized Controlled Trials as Topic
chemical_list: D000318:Adrenergic beta-Agonists; D018680:Cholinergic Antagonists