Clinical predictors of the effectiveness of tiotropium in adults with symptomatic asthma: a real-life study

Background: Long-acting muscarinic antagonist (LAMA) tiotropium improved lung function and reduced risks of exacerbation when added on to inhaled corticosteroids (ICS) with or without long-acting B2 agonists (LABAs) in patients with uncontrolled asthma. However, studies predicting the effectiveness of tiotropium based on patients’ clinical characteristics were limited. Methods: We conducted this retrospective study at a single medical center from July 2016 to July 2017, and used asthma control test (ACT) to evaluate the effectiveness of tiotropium add-on therapy in patients with uncontrolled asthma. The effectiveness was shown by an increase in ACT score from baseline of 3 or greater after 3 months of tiotropium add-on therapy. Results: Patients with uncontrolled asthma despite the use of low- or medium- to high-dose of ICS plus LABA (n=160) were analyzed. Among patients having good response (n=112, ACT score increased ≥3 points) to tiotropium (TGR group) and patients having poor response (n=48, ACT increased 30 were predictors of the effectiveness of tiotropium. Patients with high serum total IgE level >430 µg/L and eosinophil count >0.6×10 9 /L had a negative impact on response to tiotropium. Multivariate logistic regression analysis demonstrated that the independent factor of poor response to tiotropium was high serum IgE level >430 µg/L. Conclusions: Tiotropium add-on therapy in patients with uncontrolled asthma was effective. However, patients with serum total IgE level >430 µg/L were less likely to benefit from tiotropium.