Meta-analysis:: Effect of long-acting β-agonists on severe asthma exacerbations and asthma-related deaths

Background: Long-acting beta-agonists may increase the risk for fatal and nonfatal asthma exacerbations. Purpose: To assess the risk for severe, life-threatening, or fatal asthma exacerbations associated with long-acting beta-agonists. Data Sources: English- and non-English-language searches of MEDLINE, EMBASE, and Cochrane databases; the U.S. Food and Drug Administration Web site; and references of selected reviews through December 2005. Study Selection: Randomized, placebo-controlled trials that lasted at least 3 months and evaluated long-acting P-agonist use in patients with asthma. All trials allowed the use of as-needed short-acting beta-agonists. Data Extraction: outcomes measured were Peto odds ratio (OR) and risk difference of severe exacerbations requiring hospitalization, life-threatening exacerbations requiring intubation and ventilation, and asthma-related deaths. The OR for asthma-related deaths was obtained from the Salmeterol Multi-center Asthma Research Trial (SMART). Data Synthesis: Pooled results from 19 trials with 33 826 participants found that long-acting beta-agonists increased exacerbations requiring hospitalization (OR, 2.6 [95% Cl, 1.6 to 4.3]) and life-threatening exacerbations (OR, 1.8 [Cl, 1.1 to 2.9]) compared with placebo. Hospitalizations were statistically significantly increased with salmeterol (OR, 1.7 [Cl, 1.1 to 2.7]) and formoterol (OR, 3.2 [Cl, 1.7 to 6.0]) and in children (OR, 3.9 [Cl, 1.7 to 8.8]) and adults (OR, 2.0 [Cl, 1.1 to 3.9]). The absolute increase in hospitalization was 0.7% (Cl, 0.1% to 1.3%) over 6 months. The risk for asthma-related deaths was increased (OR, 3.5 [Cl, 1.3 to 9.3]), with a pooled risk difference of 0.07% (Cl, 0.01% to 0.1%). Limitations: The small number of deaths limited the reliability in assessing this risk, and 28 studies did not report information on the outcomes of interest. Conclusions: Long-acting beta-agonists have been shown to increase severe and life-threatening asthma exacerbations, as well as asthma-related deaths.