Patients were eligible if they were @ to @ years of age , had COPD ( defined by a forced expiratory volume in @ second -LSB- FEV@ -RSB- of less than @ % and a ratio of FEV@ to forced vital capacity of less than @ % ) , and had a smoking history of @ or more pack-years , were receiving supplemental oxygen or treatment with glucocorticoids or antibiotic agents , or had had an emergency department visit or hospitalization for COPD within the past year .