RT Journal Article SR Electronic T1 Chronic obstructive pulmonary disease • 6: The aetiology of exacerbations of chronic obstructive pulmonary disease JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 73 OP 80 DO 10.1136/thorax.58.1.73 VO 58 IS 1 A1 A J White A1 S Gompertz A1 R A Stockley YR 2003 UL http://thorax.bmj.com/content/58/1/73.abstract AB Exacerbations of COPD are thought to be caused by interactions between host factors, bacteria, viruses, and changes in air quality to produce increased inflammation in the lower airway. The evidence for this and the potential mechanisms by which they result in the characteristic symptoms of exacerbations is reviewed. A better understanding of the causes and processes is needed for the appropriate use of existing treatments and the development of new ones. Future studies need to define populations clearly, stratify for known confounding factors, and should aim to identify clinical correlates so that clinical practice can be modified appropriately.