Methods: Four Phase III double-blind, placebo-controlled, parallel-group trials: PrimoTinA-asthma® (2× 48-week trials; NCT00776984/NCT00772538; n=912) tiotropium Respimat® 5µg or placebo Respimat® add-on to ICS (≥800μg budesonide or equivalent) + LABA; MezzoTinA-asthma® (2× 24-week trials; NCT01172808/NCT01172821; n=2100) tiotropium Respimat® 5µg or 2.5µg or placebo add-on to ICS (400-800μg budesonide or equivalent). Patients had symptomatic asthma requiring treatment with at least ICS for ≥4 weeks before screening; COPD was excluded. Post hoc mixed model with repeated measures modeling analyses of peak and trough FEV1 were performed across continuous ranges of IgE 0-2000μg/L and eosinophils 0-2.00×109/L following treatment with tiotropium Respimat® 5µg.
Results: Tiotropium Respimat® 5µg consistently improved peak and trough FEV1, compared with placebo, across all IgE and eosinophil ranges in all trials (mean difference >0).
Conclusions: Once-daily tiotropium Respimat® add-on to at least ICS improved lung function in patients with moderate or severe symptomatic asthma, independent of serum IgE or blood eosinophil levels. These results support the lung-function improvements previously reported from subgroup analyses using binary cut-offs of serum IgE ≤ and >430μg/L and blood eosinophils ≤ and >0.6×109/L.