"Once-daily indacaterol versus tiotropium for patients with severe chronic obstructive pulmonary disease (INVIGORATE)"
Lancet Aug 21
http://www.lancet.com/journals/lanres/article/PIIS2213-2600(13)70158-9/fulltext 
"Interpretation

Indacaterol and tiotropium provided clinically relevant improvements in lung function with comparable safety profiles. Tiotropium afforded greater protection from exacerbations, although the absolute number of events was small and the difference between treatments is of uncertain clinical importance. The present data offer evidence consistent with current guidelines.

Funding

Novartis Pharma AG."