In the ED all patients underwent baseline standard clinical evaluation; blood tests (blood cell count, routine biochemical tests and arterial blood gas tensions); pulse oximetry; 12-lead electrocardiography; chest radiographs and hand-held spirometry (SpirHOMEter, COSMED, Italy). Further investigations (including pneumologist’s assessment) were performed when required, according to the clinical judgement of the ED physician. Only patients with a COPD exacerbation evaluated in ED for at least 12-24 hours and with stable clinical conditions were considered elegible to be included in the study.