In this multicentre double-blind , double-dummy , parallel-group study , 523 patients ( age 40 years or older , Global Initiative for Chronic Obstructive Lung Disease [ GOLD ] stages II-III , without exacerbations in the previous year ) were randomly assigned ( 1:1 ; via automated , interactive response technology and stratified for smoking status ) to once-daily QVA149 110/50 g or twice-daily SFC 50/500 g for 26 weeks .