An exacerbation was defined as an increase in or new onset of more than one symptom of COPD (cough, sputum, wheezing, dyspnea, or chest tightness), with at least one symptom lasting 3 days or more and leading the patient’s attending physician to initiate treatment with systemic glucocorticoids, antibiotics, or both (criterion for moderate exacerbation) or to hospitalize
the patient (criterion for severe exacerbation).The determination of the end of the exacerbation
was made on the basis of the clinical assessment of the investigator. Data on exacerbations (according to the trial definition), as well as health care resources used to treat these exacerbations,were collected by means of a questionnaire that was administered during regular clinic visits and telephone contacts. When an investigator reported a case of pneumonia, he or she was questioned as to whether the event had been confirmed by imaging.