The Effect of Tiotropium on Hyperinflation and Exercise Capacity in Chronic Obstructive Pulmonary Disease

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation, which results in the progressive development of dyspnea and exercise limitation. Objective and Methods: To compare the effect of tiotropium with placebo on forced vital capacity (FVC) in patients with moderate-to-severe COPD and lung hyperinflation, using exercise endurance, dyspnea and health-related quality of life (HRQoL) as secondary endpoints. One hundred patients were randomized to receive either tiotropium 18 µg once daily or placebo for 12 weeks. Results: Trough (predose) FVC was significantly improved with tiotropium compared to placebo on day 42 (0.27 ± 0.08 liters) and 84 (0.20 ± 0.08 liters; p < 0.05 for both). Trough inspiratory capacity (IC) was also significantly improved with tiotropium compared to placebo on day 42 (0.16 ± 0.07 liters) and 84 (0.15 ± 0.07 liters; p < 0.05 for both). Tiotropium increased the mean distance walked during the shuttle walking test by 33 ± 12 (day 42) and 36 ± 14 m (day 84) compared to placebo (p < 0.05 for both). On day 84, 59% of the patients in the tiotropium group and 35% of the patients in the placebo group had significant and clinically meaningful improvements in the St. George’s Respiratory Questionnaire total score (p < 0.05). Numerical decreases in the focal score in the Transition Dyspnea Index in patients receiving tiotropium versus placebo suggest that tiotropium also improved dyspnea during activities of daily living. Conclusion: Tiotropium 18 µg once daily reduced hyperinflation with consequent improvements in walking distance and HRQoL in patients with COPD and lung hyperinflation.