Incidence of serious adverse events was similar between groups ( @ -LSB- @ % -RSB- patients on QVA@ , @ -LSB- @ % -RSB- on glycopyrronium , and @ -LSB- @ % -RSB- on tiotropium ) ; COPD worsening was the most frequent serious adverse event ( @ -LSB- @ % -RSB- patients on QVA@ , @ -LSB- @ % -RSB- on glycopyrronium , @ -LSB- @ % -RSB- on tiotropium ) .