2. Patients with a forced expiratory volume in 1 second (FEV1) at Visit 1 of ≥ 50% of the predicted normal value. This criterion for FEV1 had to be demonstrated after a washout period of at least 6 hours during which no short acting β2-agonist had been inhaled, and a minimum of 48 hours for a long acting β2-agonist.