Active Controlled Trial of CHF5993 Pressurized Metered-dose Inhaler ( pMDI) vs Symbicort®Turbuhaler® in Patients With Chronic Obstructive Pulmonary Disease ( COPD) (TRIVERSYTI)

Primary Objective • To demonstrate the superiority of CHF 5993 pressurised metered dose inhaler (pMDI) over Symbicort® Turbuhaler® in terms of pulmonary function (change from baseline in pre-dose morning forced expiratory volume in the first second of a forced vital capacity manoeuvre \[FEV1\] and 2-hour post-dose morning FEV1 at Week 24). Secondary Objectives Key secondary objective: • To demonstrate the superiority of CHF 5993 pMDI over Symbicort® Turbuhaler® in terms of pulmonary function (change from baseline in pre-dose morning FEV1 and 2-hour post-dose morning FEV1 at Week 24) in the subgroup of Chinese population. Other secondary objectives: * To evaluate the effect of CHF 5993 pMDI on other lung function parameters, patient's health status and clinical outcome measures; * To collect data in order to assess the impact of study treatments on health economic outcomes; * To assess the safety and the tolerability of the study treatments.