This is a comparator study to assess the relative efficacy of the combination product fluticasone propionate/salmeterol 50/500 and tiotropium bromide on the rate of exacerbations of chronic obstructive pulmonary disease (COPD) over a two year study interval.

• Drug: Tiotropium bromide 18mcg
• Drug: Fluticasone propionate/ salmeterol combination 50/500mcg

Inclusion criteria:

• Established clinical history of moderate to severe COPD.
• Post bronchodilator FEV1 of < 50% of predicted normal.
• FEV1 / FVC ratio <70%.
• Reversibility to 400mcg albuterol of less or equal to 10 predicted at Visit 1.
• Free from exacerbation in the 6 weeks prior to screening.
• Current or former smoker with a smoking history of = 10 pack-years and has a history of COPD exacerbations.

Exclusion criteria:

• Current asthma, eczema, atopic dermatitis and/or allergic rhinitis.
• Has a known respiratory disorder other than COPD (e.g. lung cancer, sarcoidosis, tuberculosis or lung fibrosis).
• Has narrow-angle glaucoma, prostatic hyperplasia or obstruction of the neck of the bladder that in the opinion of the investigator should prevent the subject from entering the study.
• Has undergone lung transplantation and/or lung volume reduction.
• Female who is a nursing mother.
• Requires regular (daily) long-term oxygen therapy (LTOT).
• Is receiving beta-blockers (except eye drops).
• Has a serious, uncontrolled disease likely to interfere with the study.
• Has received any other investigational drugs within the 4 weeks prior to Visit 1.
• Has, in the opinion of the investigator, evidence of alcohol, drug or solvent abuse.
• Has a known or suspected hypersensitivity to beta2-agonists, inhaled corticosteroids, anticholinergic agents or any components of the formulations (e.g. lactose or milk protein).