Study	Reason for exclusion
Barnes 2010	These studies cover phase I (2‐week dose selection) and III (comparison arm changing from placebo to tiotropium/indacaterol during treatment period) of the Donohue 2010 trial, or did not report data with tiotropium
Chapman 2010	Cross‐over study design
Di Marco 2006	Single dose of treatment only
Donohue 2011	Cross‐over study design
Golubev 2006	Cross‐over study design
Gross 2003	Study duration ‐ 4 weeks
Meyer 2008	Cross‐over study design
Meyer 2011	Study duration ‐ 2 weeks
Reisner 2011	Cross‐over study design; study duration ‐ 1 week
Rossi 2012	Cross‐over study design
Tashkin 2009	Study duration ‐ 2 weeks
ten Hacken 2007	Cross‐over study design
van der Vaart 2011	Cross‐over study design
van Noord 2003	Cross‐over study design
van Noord 2005	Cross‐over study design
van Noord 2006	Cross‐over study design
Vogelmeier 2010	Cross‐over study design