P56 Efficacy and safety of long-acting beta agonists + long acting muscarinic antagonists vs. long-acting beta agonists + inhaled corticosteroids in COPD: a meta-analysis
P56 Efficacy and safety of long-acting beta agonists + long acting muscarinic antagonists vs. long-acting beta agonists + inhaled corticosteroids in COPD: a meta-analysis