Introduction: Airway obstruction is usually assessed by measuring forced expiratory volume in 1 s (FEV1), 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 FEV1, FVC, PEF and FEV1/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 FEV1 (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 FEV1 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.
Keywords: Airway obstruction; Asthma; Muscarinic antagonist; Respiratory function tests; Tiotropium bromide.
Asthma is characterised by problems with the way that the lungs work, particularly narrowing of the airways. Doctors can measure the effect of asthma on someone’s breathing in different ways. We looked to see whether these different methods work for different people with asthma, and whether treatment affects all measurements in a similar way. Lung function was measured after treatment with a drug that opens the airways (tiotropium), and comparisons were made between adults and adolescents with asthma. We also looked at people with severe asthma and those whose asthma was less severe. Tiotropium improved all the measures of lung function in both age groups and across severities. One measure improved more in adults than in adolescents. This may be because adolescents had better lung function at the start and thus less room for improvement, or because the adolescents had not had asthma for as long, and so may have had less long-term damage to their airways than adults.Trial Registration Numbers: NCT00772538, NCT00776984, NCT01172808, NCT01172821, NCT01316380, NCT01257230.