Tiotropium Respimat Efficacy and Safety in Asthma: Relationship to Age

Background: Data are limited on the differential response to long-acting bronchodilators in older versus younger adults with asthma. Objective: To determine whether the response to tiotropium Respimat differed in older versus younger patients with asthma. Methods: Post hoc analyses of 4 randomized, double-blind, placebo-controlled studies in adults with asthma were carried out. Two studies compared tiotropium Respimat 5 μg once daily with placebo, both added to high-dose inhaled corticosteroid (ICS) plus long-acting β₂-agonist (ie, severe asthma). The other 2 evaluated tiotropium Respimat 2.5 or 5 μg once daily, salmeterol 50 μg twice daily, or placebo, all added to medium-dose ICS (moderate asthma). Data were analyzed in 2 pools: (1) severe and (2) moderate asthma. Efficacy end points: trough and peak FEV₁; trough forced vital capacity; Asthma Control Questionnaire total score and responder percentage, all at week 24. One set of analyses was performed with age as a continuous covariate; the second was conducted in categories less than 40, 40 to 60, and more than 60 years, with treatment-by-age subgroup interaction P values obtained. Safety was analyzed in age categories. Results: Across the age categories, treatment-by-age subgroup interaction P values for trough FEV₁ were.13 and.77 for patients with severe and moderate asthma, respectively, not indicating significant impact of age on overall treatment effect, with this observation replicated in the 2 continuum analyses. The other end points (including safety) were also not impacted by age. Conclusions: Once-daily tiotropium Respimat add-on to ICS or ICS/long-acting β₂-agonist therapy was effective and well tolerated in patients with asthma independent of age.