Evaluate whether the effect of inhaled tiotropium bromide on the change in trough FEV1 from baseline to week 12 compared to placebo in patients with COPD is affected by smoking status. Secondary objectives include FEV1 at interim visit and FVC at on-treatment visits, use of rescue medication, COPD symptom scores, Physicians Global Evaluation and EQ-5D scores.~Study Hypothesis:~The primary objective of the study is to show superiority of tiotropium against placebo with respect to trough FEV1 at 12 weeks. Then the 5% two-sided hypotheses test is:~H0: Mean trough FEV1 at 12 weeks in tiotropium = Mean trough FEV1 at 12 weeks in placebo H1: Mean trough FEV1 at 12 weeks in tiotropium unequal Mean trough FEV1 at 12 weeks in placebo If the null hypothesis is rejected in favour of the alternative hypothesis (H1) based on all patients, the same hypotheses will be tested in both sub-populations of current and ex-smokers respectively.~Comparison(s):~Tiotropium bromide - 18 mcg capsule inhaled via the HandiHaler vs Placebo powder capsules for oral inhalation, via the HandiHaler.
Evaluate whether the effect of inhaled tiotropium bromide on the change in trough forced expiratory volume (FEV1), compared to placebo in patients with chronic obstructive pulmonary disease (COPD), is affected by smoking status.