Tiotropium improves lung function, exacerbation rate, and asthma control, independent of baseline characteristics including age, degree of airway obstruction, and allergic status

Background Many patients with asthma remain symptomatic despite treatment with inhaled corticosteroids (ICS) with or without long-acting β2-agonists (LABAs). Tiotropium add-on to ICS plus a LABA has been shown to improve lung function and reduce exacerbation risk in patients with symptomatic asthma. Objective To determine whether the efficacy of tiotropium add-on therapy is dependent on patients' baseline characteristics. Methods Two randomized, double-blind, parallel-group, twin trials (NCT00772538 and NCT00776984) of once-daily tiotropium Respimat® 5 μg add-on to ICS plus a LABA were performed in parallel in patients with severe symptomatic asthma. Exploratory subgroup analyses of peak forced expiratory volume in 1 s (FEV1), trough FEV1, time to first severe exacerbation, time to first episode of asthma worsening, and seven-question Asthma Control Questionnaire responder rate were performed to determine whether results were influenced by baseline characteristics. Results 912 patients were randomized: 456 received tiotropium and 456 received placebo. Tiotropium improved lung function, reduced the risk of asthma exacerbations and asthma worsening, and improved asthma symptom control, compared with placebo, independent of baseline characteristics including gender, age, body mass index, disease duration, age at asthma onset, and FEV1 % predicted at screening and reversibility. Conclusion Once-daily tiotropium 5 μg compared with placebo improved lung function, reduced the risk of asthma exacerbations and asthma worsening, and improved asthma symptom control, independent of a broad range of baseline characteristics, as add-on to ICS plus LABAs in patients with severe symptomatic asthma. Trial registry ClinicalTrials.gov; numbers NCT00772538 and NCT00776984 URL: www.clinicaltrials.gov.