Add-on Tiotropium Therapy Improves Asthma Regardless of Many Patient Characteristics

At least 40% of asthma patients remain symptomatic despite treatment with inhaled corticosteroids with or without long-acting β₂-agonists. The long-acting anticholinergic bronchodilator tiotropium (Spiriva Respimat/Boehringer Ingelheim) has been incorporated into the Global Initiative for Asthma 2015 treatment strategy as an add-on therapy option for patients with a history of asthma exacerbations, and the clinical efficacy and safety of add-on tiotropium therapy have been established in adults across differing asthma severity levels.

Now, two randomized, double-blind, parallel-group twin trials reported in Respiratory Medicine have shown that add-on tiotropium therapy helps to control asthma in symptomatic patients regardless of many patient characteristics. These findings indicate that add-on tiotropium therapy could be useful for a wide range of asthma patients who still have asthma symptoms despite treatment with other agents.

In these two international, multicenter trials, add-on therapy with tiotropium improved lung function and asthma symptom control and reduced the risk of asthma exacerbation episodes and worsening of asthma in symptomatic asthma patients taking an inhaled corticosteroid with a long-acting β₂-agonist, regardless of patient age, allergic status, and degree of airway obstruction at baseline.

The trials enrolled 912 patients with severe, symptomatic asthma who had been taking at least 800 μg of budesonide or the equivalent as well as a long-acting β₂-agonist for at least 4 weeks. Currently symptomatic patients between the ages of 18 and 75 years with a history of asthma of at least 5 years and an initial diagnosis before age 40 years were eligible to participate in the study. Moderate or persistent airflow limitation at the initial screening visit and at least one exacerbation in the last year requiring systemic glucocorticoid therapy were also requirements for study participation.

Patients were randomly assigned in a 1:1 ratio to receive either tiotropium, 5 μg once daily via the Respimat Soft Mist inhaler (Boehringer Ingelheim), or placebo for 48 weeks.

The study investigators measured the following asthma parameters:

• Peak force expiratory volume in 1 second (FEV₁)
• Trough FEV₁
• Time to first severe exacerbation
• Time to first episode of worsening asthma
• Results from the seven-question Asthma Control Questionnaire

Subgroup analysis of the relation between these parameters and patients’ baseline characteristics indicated that, compared with placebo, once-daily tiotropium improved lung function and control of asthma in these patients independently of a broad range of characteristics including gender, body mass index, disease duration, age at asthma onset, FEV₁ percentage predicted at screening, and FEV₁ reversibility.