Tiotropium improves FEV1 in patients with COPD irrespective of smoking status

Abstract

This study evaluated whether the effect of tiotropium on the change in trough forced expiratory volume in 1s (FEV1), vs. placebo, is affected by smoking status. In a 3-month, double-blind study in 31 centres in Portugal, 311 (289 completed) patients were randomised to tiotropium 18 microg once daily or placebo. Baseline mean (standard deviation (SD)) FEV1 was 1.11 (0.39) l in the tiotropium group and 1.13 (0.39) l in the placebo group. Patients had an average smoking history of 55 (25.7) pack-years; 80 (26%) were smokers and 224 (74%) were ex-smokers. The primary end-point was change in morning pre-dose (i.e. trough) FEV1 after 12 weeks. Trough FEV1 at 12 weeks was significantly improved with tiotropium vs. placebo: the difference in means was 102 ml, P=0.0011, 95% confidence interval (CI) (41, 164). The difference in means in smokers was 138 ml, P=0.0105, CI (32, 244); in ex-smokers it was 66 ml, P=0.0375, CI (3, 129). The difference between smokers and ex-smokers was not statistically significant (P=0.6982) and may be due to greater variability and differences in disease severity. The significant improvement in lung function in patients treated with tiotropium vs. placebo in both smokers and ex-smokers suggests that tiotropium is an effective and well-tolerated therapy in chronic obstructive pulmonary disease (COPD), regardless of smoking status.