A Study to Compare the Impact of Fulticasone Furoate/Vilanterol vs. Tiotropium on Arterial Stiffness in COPD

This is a Phase IIIb comparator, double-blind, double-dummy, randomised (1:1), parallel group, multi-centre study. At Visit 1 (Screening Visit), subjects who meet the pre-defined Inclusion Criteria and none of the Exclusion Criteria will enter a 2-week, single-blind placebo Run-in Period. The purpose of the Run-In Period is to monitor albuterol/salbutamol use at baseline, and to ensure that subjects' COPD is at a stable stage at randomization. Subject's adherence with study procedures, diary completion will also be evaluated during the Run-In Period. At the end of the Run-in period, subjects will be assessed and those who meet the randomisation criteria will receive one of the following two double-blind treatments for 12 weeks: * FF (100 mcg)/VI (25 mcg) administered QD via a NDPI in the morning * Tiotropium (18 mcg) administered QD via a HandiHaler in the morning To ensure blinding of the treatments and to ensure a double-dummy design matching NDPI and HandiHaler will be utilised. Each subject will be instructed to self administer blinded study drug during the double blind treatment period as follows: * Each morning take 1 inhalation from NDPI containing FF (100 mcg)/VI (25 mcg) followed by 1 inhalation from placebo capsule delivered via HandiHaler. * Each morning take 1 inhalation from matching placebo NDPI followed by 1 inhalation from a capsule containing tiotropium 18 mcg delivered via HandiHaler. An inhaled short acting beta2-receptor agonist, salbutamol/albuterol will be provided to subjects to use as needed throughout the Run-in and Treatment periods for relief of COPD symptoms. Ipratropium bromide is permitted if the subject is on a stable dose from Screening (Visit 1) and remains on the stable dose throughout the study. Subjects who experience an exacerbation of their COPD (which requires medication in addition to an increase in rescue medication) or a lower respiratory tract infection (LRTI) during the run-in period are not eligible to enter the treatment period. Any subject who experiences a similar COPD exacerbation (sec 4.4) or LRTI at any time on therapy will be withdrawn from the study. The aPWV will be measured at Screening and clinic Visits 3-5. Disease specific health status will be evaluated using the St. George's Respiratory Questionnaire (SGRQ-C), Euro Qol Questionnaire (EQ-5D) for COPD patients and the COPD Assessment Test (CAT) at Visit 2 (Day 1) and at Visit 5 (Weeks 12). The 12-lead ECG will be evaluated at Visit 1 (Screening) only. Vital signs (blood pressure and pulse rate), spirometry measurements, and clinical laboratory tests (hematology and chemistry) and other study-specific safety assessments will be obtained at selected clinic visits. A follow-up phone call will occur approximately 7 days after the last clinic visit. The overall study duration from Screening to Follow-up for each subject is approximately 15 weeks. Subjects will be considered to have completed the study upon completion of assessments and procedures up to and including completion of Follow-up Phone Contact (7 ± 2 days post Visit 5).