The purpose of this study is to evaluate the 24-hour spirometry effect (FEV1) of Fluticasone Furoate/Vilanterol 100/25mcg once daily compared with Salmeterol/Fluticasone Propionate 50/500mcg twice daily over a 12-week treatmen period in subjects with COPD.

This is a randomized, double-blind, double-dummy, multi-centre parallel group study. Subjects who meet the eligilibilty criteria at Screening and meet the randomization criteria at the end of a 2-week Run-In period will enter a 12-week Treatment period. There will be a 7-day Follow-up period after the treatment period.

Inclusion Criteria:

• Signed and dated written informed consent
• Male or females ≥ 40 years of age
• Established clinical history of COPD by ATS/ERS definition
• Females are eligible to enter and participate if of non-childbearing potential, or if of child bearing potential, has a negative serum pregnancy test at screening, and agrees to one of the acceptable contraceptive methods listed in protocol, used consistently and correctly
• Former or current smoker > 10 pack years
• Post-albuterol spirometry criteria: FEV1/FVC ratio ≤ 0.70 and FEV1 ≤ 70% of predicted normal (NHANES III)
• have been hospitalised or have been treated with oral corticosteroids or antibiotics for their COPD within the last 3 years prior to Screening (Visit 1)

Exclusion Criteria:

• Current diagnosis of asthma
• Subjects with other respiratory disorders including active tuberculosis, α1-antitrypsin deficiency, lung cancer, bronchiectasis, sarcoidosis, lung fibrosis, pulmonary hypertension, interstitial lung diseases or other active pulmonary diseases
• Lung volume reduction surgery within previous 12 months
• Clinically significant abnormalities not due to COPD by chest x-ray
• Hospitalized for poorly controlled COPD within 12 weeks of Screening
• Poorly controlled COPD 6 weeks prior to Screening, defined as acute worsening of COPD that is managed by the subject with corticosteroids or antibiotics or that requires treatment prescribed by a physician
• Lower respiratory infection requiring antibiotics 6 weeks prior to Screening
• Uncontrolled or clinically significant (in opinion of PI) cardiovascular, hypertension, neurological, psychiatric, renal, hepatic, immunological, endocrine, peptic ulcer disease, or hematological abnormalities
• Carcinoma not in complete remission for at least 5 years
• Subjects with history of hypersensitivity to study medications (e.g., beta-agonists, corticosteroid) or components of inhalation powder (e.g., lactose, magnesium stearate)
• Subjects with history of severe milk protein allergy that, in opinion of study physician, contraindicates subject's participation - Known/suspected history of alcohol or drug abuse in the last 2 years
• Women who are pregnant or lactating or plan to become pregnant
• Subjects medically unable to withhold albuterol and/or ipratropium 4 hours prior to spirometry testing at each study visit
• Use of certain medications such as bronchodilators and corticosteroids for the protocol-specific times prior to Visit 1 (the Investigator will discuss the specific medications)
• Long Term Oxygen Therapy (LTOT) or nocturnal oxygen therapy >12 hours a day
• Participation in the acute phase of a pulmonary rehabilitation program within 4 weeks prior to Screening or during the study - Non-compliance or inability to comply with study procedures or scheduled visits
• Affiliation with investigator site

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