This recommendation places value on a short-acting muscarinic antagonist plus short-acting β2-agonist reducing the risk of acute exacerbations of COPD together with the comparative small benefits of a short-acting muscarinic antagonist plus a short-acting β2-agonist improving quality of life, exercise tolerance, and lung function compared with a short-acting β2-agonist alone. This recommendation also acknowledges that there are no significant differences in serious adverse events with the use of a short-acting muscarinic antagonist plus a short-acting β2-agonist vs a short-acting β2-agonist alone.