- Subject has poorly controlled or unstable COPD, defined as the occurrence of any of the following: Either: acute worsening of COPD (an exacerbation) that is managed by the subject at home requiring treatment with corticosteroids and/or antibiotics in the 4 weeks prior to the screening visit; or more than two exacerbations in the previous 2 months prior to the screening visit that required a course of oral corticosteroids and/or antibiotics, or for which the subject was hospitalised.