Chronic obstructive pulmonary disease (COPD) is a progressive airway inflammatory condition that is associated with accelerated decline of lung function and is characterized by worsening dyspnea with episodes of increased number and severity of symptoms, termed exacerbations.

The main objectives of managing COPD are a reduction in the severity of symptoms and the prevention of exacerbations. Bronchodilator therapy is central to the management of COPD; this treatment produces modest increases in lung function as measured by spirometry and a reduction in the dynamic hyperinflation that leads to the dyspnea of COPD. Patients with COPD often present to their physician with dyspnea, and bronchodilators are often the first therapy prescribed. Initially, short-acting bronchodilators, such as albuterol, may be used, but in patients with persistent symptoms, long-acting bronchodilators provide more uniform relief.

Currently there are two classes of long-acting bronchodilators available — long-acting β₂-agonists and long-acting anticholinergic agents, and both classes of agents, as compared with placebo, have been shown to provide relief from symptoms in patients with COPD...