One-year analysis of longitudinal changes in spirometry in patients with COPD receiving tiotropium

Airway medications have not been shown to reduce the loss of lung function in patients with COPD. We explored whether tiotropium 18 μg once daily could slow the rate of decline of lung function over a 1-year period. We performed a post-hoc analysis of data from 921 ambulatory COPD patients participating in two, 1-year, double-blind, tiotropium vs. placebo-controlled trials. Serial spirometry was obtained at baseline (before first dose of study drug), on day 8, at 6 weeks, and at 3, 6, 9 and 12 months after start of the study. Baseline demographics and lung function were comparable. Baseline FEV ₁ was 1.01±0.41 (SD) L (39±14% predicted). Mean decline in trough FEV ₁ (i.e. FEV ₁ 23-24 h after prior use of medication) between days 8 and 344 was 58 ml/year in the placebo group and 12 ml/year in the tiotropium group (p=0.005 vs. placebo); and between days 50 and 344 was 59 ml/year in the placebo group and 19 ml/year in the tiotropium group (p=0.036 vs. placebo). Based on a retrospective analysis of 1-year, placebo-controlled clinical trials, tiotropium was associated with a reduced rate of loss of FEV ₁. Longer-term trials specifically designed to study this effect are required to confirm this observation.