This is a phase IIIa, randomised, double-blind, double-dummy, parallel group multicenter study evaluating once daily FF/UMEC/VI (100 microgram [mcg]/62.5 mcg/25 mcg) inhalation powder versus twice daily budesonide/formoterol (400 mcg/12 mcg). The primary purpose of this study is to demonstrate improvements in lung function and health status for subjects treated with FF/UMEC/VI compared with budesonide/formoterol for 24 weeks. Once-daily 'closed' triple therapy of a Inhaled Corticosteroid/ Long-acting Muscarinic Receptor Antagonists/ Long Acting Beta-Agonist (ICS/LAMA/LABA) combination FF/UMEC/VI (100 mcg/62.5 mcg/25 mcg) in a single device is being developed with the aim of providing a new treatment option for the management of advanced (GOLD Group D) COPD which will reduce the exacerbation frequency, allow for a reduced burden of polypharmacy, convenience, and increase the potential for improvement in lung function, Health Related Quality of Life (HRQoL) and symptom control over established dual/monotherapies.