In this 12-month , double-blind , parallel-group study , 2485 patients with a history of exacerbation of COPD received triple therapy consisting of tiotropium ( at a dose of 18 g once daily ) , salmeterol ( 50 g twice daily ) , and the inhaled glucocorticoid fluticasone propionate ( 500 g twice daily ) during a 6-week run-in period .