title: Efficacy and safety of conventional long acting β2- agonists: systematic review and meta-analysis.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) is usually considered one of the leading causes of death worldwide, so finding proper therapeutic strategies for this disease is of high importance. In this meta-analysis, we reviewed the existing literature on the efficacy and safety of conventional long acting beta agonists (LABAs) in COPD patients.
  
  
  METHODS
  We searched MEDLINE and Google scholar to identify relevant articles. We limited data to double-blinded randomized controlled trials (RCTs). Data of 14, 832 COPD subjects including 7540 patients under a β2 agonist (cases) and 7292 taking placebo (controls) retrieved from 20 randomized controlled trials and were enrolled into this meta-analysis. Evaluated outcomes included overall mortality, exacerbations and tolerance to the drug.
  
  
  RESULTS
  The analysis of survival showed no significant difference between those taking LABAs or placebo (relative risk (RR): 0.945, 95% confidence interval (CI): 0.821-1.088, P=0.432). Exacerbation rate, however, was significantly lower among the cases than among the controls (RR: 0.859, 95%CI: 0.800-0.922, p<0.001). Similar observation was detected in analyzing the rate of drug withdrawal in patients of the two groups with patients under placebo having significantly higher rate of drug discontinuation due to adverse events or disease symptoms (RR:0.821, 95% CI: 0.774-0.871; p<0.007).
  
  
  CONCLUSIONS
  In conclusion, we found that the use of conventional LABA therapy in COPD patients is associated with a lower exacerbation rate of the disease as well as higher tolerance to the drug, but no survival advantage is expectable. Substitution of LABAs with new agents is recommended.
authors.affiliation: Atherosclerosis Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Karbasi-Afshar
authors.affiliation: Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences; Tehran, Iran.
authors.forename: Jafar
authors.initials: J
authors.lastname: Aslani
authors.affiliation: Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences; Tehran, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Ghanei
keywords: COPD; chronic obstructive pulmonary disease; drug; meta analysis; β2-Agonists