An exacerbation of COPD was defined as the increase or new onset of more than one symptom of COPD ( cough , sputum , wheezing , dyspnoea , or chest tightness ) , with at least one of the symptoms lasting for 3 days or more and needing treatment with antibiotics or systemic glucocorticoids ( moderate exacerbations ) , or admission to hospital ( severe exacerbations ) .