Comparative Responses in Lung Function Measurements with Tiotropium in Adolescents and Adults, and Across Asthma Severities: A Post Hoc Analysis

INTRODUCTION: Airway obstruction is usually assessed by measuring forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC) and peak expiratory flow (PEF). This post hoc study investigated comparative responses of lung function measurements in adults and adolescents (full analysis set, N = 3873) following treatment with tiotropium Respimat(®). METHODS: Lung function outcomes were analysed from five phase III trials in adults (≥ 18 years) with symptomatic severe, moderate and mild asthma (PrimoTinA-asthma(®), MezzoTinA-asthma(®) and GraziaTinA-asthma(®), respectively), and one phase III trial in adolescents (12–17 years) with symptomatic moderate asthma (RubaTinA-asthma(®)). Changes from baseline versus placebo in FEV(1), FVC, PEF and FEV(1)/FVC ratio with tiotropium 5 µg or 2.5 µg added to at least stable inhaled corticosteroids at week 24 (week 12 in GraziaTinA-asthma) were analysed. RESULTS: All lung function measures improved in all studies with tiotropium 5 µg (mean change from baseline versus placebo), including peak FEV(1) (110–185 mL), peak FVC (57–95 mL) and morning PEF (15.8–25.6 L/min). Changes in adolescents were smaller than those in adults, and were statistically significant primarily for FEV(1) and PEF, but not for FVC. CONCLUSION: Consistent improvements were seen across all lung function measures with the addition of tiotropium to other asthma treatments in adults across all severities, whereas the improvements with tiotropium in adolescents primarily impacted measures of flow rather than lung volume. This may reflect less pronounced airway remodelling and air trapping in adolescents with asthma versus adults.