This study evaluates the effect of two medicines on COPD (Chronic Obstructive Pulmonary Disease) exacerbations. This study will last up to 56 weeks, and subjects will visit the clinic 10 times. Subjects will be given breathing tests and will record their breathing symptoms daily on diary cards. All study related medicines and medical examinations will be provided at no cost. The two drugs used in this study have been approved by FDA for use in patients with COPD.

A Randomized, Double-Blind, Parallel Group, 52-week Study to Compare the Effect of the Fluticasone Propionate/Salmeterol DISKUS Combination Product 250/50mcg BID with Salmeterol DISKUS 50mcg BID on the Annual Rate of Moderate/Severe Exacerbations in Subjects with Chronic Obstructive Pulmonary Disease (COPD)

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.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.