title: Toward a standardized definition and severity classification of COPD exacerbations.
authors.forename: Jun
authors.initials: J
authors.lastname: Shu
mesh_terms: D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000175:diagnosis* / Q000503:physiopathology; D012720:Severity of Illness Index