RT Journal Article SR Electronic T1 COPD exacerbations ยท 1: Epidemiology JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 164 OP 168 DO 10.1136/thx.2005.041806 VO 61 IS 2 A1 G C Donaldson A1 J A Wedzicha YR 2006 UL http://thorax.bmj.com/content/61/2/164.abstract AB The epidemiology of exacerbations of chronic obstructive pulmonary disease (COPD) is reviewed with particular reference to the definition, frequency, time course, natural history and seasonality, and their relationship with decline in lung function, disease severity and mortality. The importance of distinguishing between recurrent and relapsed exacerbations is discussed.