Background: International guidelines recommend long-acting bronchodilators in patients who remain symptomatic despite adequate treatment with short-acting bronchodilators. The purpose of this study is to estimate the effect of tiotropium, a long-acting anticholinergic inhalant, on exacerbation and hospitalisation frequency.
Methods: Electronic databases (Medline, Embase, INAHTA, CRD databases, and the Cochrane Library) were searched for randomised controlled trials, comparing tiotropium to placebo, or other bronchodilators. Outcomes were the exacerbation frequency and hospitalisation frequency. Data were pooled using the generic inverse variance method for continuous outcomes.
Results: Nine studies reported comparisons with placebo (n = 8), ipratropium (short-acting anticholinergic inhalant, n = 1), and salmeterol (long-acting β₂-agonist inhalant, n = 1). Only two studies reported adequate concealment of allocation. Tiotropium reduces the number of exacerbations per patient year by 0.31 (95% CI 0.46- 0.17) compared to placebo, and by 0.23 (95% CI 0.31- 0.15) compared to ipratropium. A significant difference in exacerbation frequency between tiotropium and salmeterol was found (-0.16; 95% CI -0.29 - -0.03) based on approximations of the results of one study.The number of hospitalisations is reduced by 0.04 (95% CI 0.08- 0.01) per patient year compared to placebo and by 0.06 (95% CI -0.09 - -0.03) per patient year compared to ipratropium.
Conclusions: Statistically significant but clinically small effects were found for tiotropium compared to placebo and ipratropium. The comparison with salmeterol is significant for exacerbation frequency but not for hospitalisation frequency. Publication bias may be present.