Should regular use of β agonists be recommended for patients with persistent asthma?

Objective. To assess the effect of regular β₂-agonist use compared with placebo on pulmonary function and β₂-receptor function in patients with asthma. Design. Meta-analysis of randomized, placebo-controlled studies of regular β₂-agonist use of at least 1-week duration in asthma patients where the placebo arm did not use any β₂-agonists. Main outcome measures. Change in mean forced expiratory volume in 1 second (FEV₁) (measured at least 6 hours after administration of the last dose of drug), response to subsequent β₂ agonist after the study period, provocative challenge causing a 20% reduction in FEV₁ (PC₂₀), and in vitro leukocyte β₂-receptor density. Main results. Data were available from 22 randomized trials that evaluated 323 participants. Change in mean FEV₁ did not differ between treatment and control groups. Compared with placebo, regular β₂-agonist treatment reduced peak FEV₁ in response to subsequent β₂-agonist use (-17.8% [95% confidence interval (CI), -27.2% to -8.5%]), the PC₂₀ to provocative stimuli (-26% [95% CI, -37% to -11%]), and leukocyte β₂-receptor density (-18.3% [95% CI, -31.6% to -5.1%]). Conclusion. Regular β₂-agonist use in patients with asthma resulted in decreased responsiveness to the drug's bronchodilating effects.