RT Journal Article SR Electronic T1 Metoprolol is not effective for preventing acute exacerbations in COPD JF BMJ Evidence-Based Medicine JO BMJ EBM FD BMJ Publishing Group Ltd SP bmjebm-2019-111313 DO 10.1136/bmjebm-2019-111313 A1 Igho J Onakpoya YR 2020 UL http://ebm.bmj.com/content/early/2020/01/02/bmjebm-2019-111313.abstract AB