Study	Reason for exclusion
Ambrosino 2008	Part of a more complex intervention with 8 weeks pulmonary rehabilitation before 12 weeks of tiotropium versus placebo treatment
Baloira 2005	Less than 12 weeks study duration
Bedard 2011	Less than 12 weeks study duration
Calverley 2000	Less than 12 weeks study duration
Casaburi 2005	Part of a more complex intervention with 8 weeks pulmonary rehabilitation before 12 weeks of tiotropium versus placebo treatment
Celli 2002	Less than 12 weeks study duration
da Fonseca 2010	Part of a more complex intervention with an exercise programme
de Guia 2004	Tiotropium versus ipratropium, no placebo group, less than 12 weeks study duration
Diba 2009	Less than 12 weeks study duration
Diba 2011	Cross‐over study design
Friedman 1998	Less than 12 weeks study duration
Fuhr 2010	Cross‐over study design
Gelb 2011	Cross‐over study design
Gurzhiy 2007	Not an RCT as the study groups were moderate versus severe COPD, less than 12 weeks study duration
Halpin 2006	Systematic review of data
Hasani 2001	Less than 12 weeks study duration
Hasani 2001b	Less than 12 weeks study duration
Hirata 2003	Tiotropium versus oxitropium, no placebo group
Kerstjens 2004	Tiotropium in combination with ipratropium or fenoterol or placebo, cross‐over study design
Langley 2002	Less than 12 weeks study duration
McNicholas 2001	Less than 12 weeks study duration
Meshcheriakova 2007	Tiotropium + ICS/LABA or tiotropium + ICS/LABA + threshold positive expiratory pressure (PEP) and inspiratory muscle trainer (IMT) devices (PID) training or tiotropium + ICS/LABA + physical training or ICS/LABA
O'Donnell 2002	Less than 12 weeks study duration
O'Donnell 2004a	Less than 12 weeks study duration
O'Donnell 2005	Less than 12 weeks study duration
O'Donnell 2005a	Cross‐over study design
Olson 2009	Less than 12 weeks study duration
Reisner 2011	Cross‐over study design
Rossi 2008	Cross‐over study design, less than 12 weeks study duration
Schilling 2000	Less than 12 weeks study duration
Schurmann 2004	Cross‐over study design, less than 12 weeks study duration
Sposato 2005	Less than 12 weeks study duration
ten Hacken 2007	Cross‐over study design
van Noord 2006	Cross‐over study design, less than 12 weeks study duration
Vincken 2001	Tiotropium versus ipratropium, no placebo group

COPD: chronic obstructive pulmonary disease
 ICS: inhaled corticosteroids
 IMT: inspiratory muscle training
 LABA: long‐acting beta₂‐agonist
 PEP: positive expiratory pressure