Advair® DISKUS® Versus Serevent® DISKUS® For Chronic Obstructive Pulmonary Disease Exacerbations

Inclusion criteria: * Diagnosis of COPD. * Current or previous cigarette smokers with a smoking history of at least 10 pack-years. * History of at least 1 COPD exacerbation in the 12 months prior to screening. * Forced expiratory volume in one second (FEV1) of less than or equal to 50% of predicted normal. Exclusion criteria: * Diagnosis of asthma. * Additional respiratory disorders other than COPD (eg, sarcoidosis, alpha-1 antitrypsin deficiency, cystic fibrosis, or active tuberculosis). * Concurrent use of long-acting beta-agonists, long-acting anticholinergics, inhaled and oral corticosteroids, theophylline, investigational medications, ritonavir, and anti-leukotrienes. * Lung resection surgery within 1 year of screening. * Abnormal and clinically significant ECG findings at screening. * Other inclusion and exclusion criteria will be evaluated at the first study visit.