This recommendation places high value on a long-acting muscarinic antagonist reducing the risk of acute exacerbations of COPD, both moderate (required course of oral steroids, antibiotics, or both) and severe (required hospitalization), together with the comparative benefit of a long-acting muscarinic antagonist improving quality of life and lung function compared with a short-acting muscarinic antagonist. This recommendation also acknowledges that there were fewer nonfatal serious adverse events in subjects treated with long-acting muscarinic antagonist than in those treated with a short-acting muscarinic antagonist.