Definition and Classification Criteria for the diagnosis of COPD have been established.3 However, there is no validated diagnostic test or biomarker of COPD exacerbations.4 The American Thoracic Society (ATS) and European Respiratory Society (ERS) define an exacerbation as an acute change in a patient’s baseline dyspnea, cough, or sputum that is beyond normal variability, and that is sufficient to warrant a change in therapy.5 The ATS and ERS classify COPD exacerbations as mild, moderate, or severe, based on the intensity of themedical intervention required to control the patient’s symptoms (Table 1). 4,5 In addition to the hallmark symptoms of a COPD exacerbation (cough, dyspnea, and increased sputum), systemic inflammation also causes extrapulmonary symptoms (Table 2). 6-8 Factors that increase the risk of a severe exacerbation are listed in Table 3. 5-7,9-11