ABSTRACT
Exacerbations of chronic obstructive pulmonary disease (COPD) are an important
cause of the considerable morbidity and mortality found in COPD (1). Some patients
are prone to frequent exacerbations that are an important cause of hospital admission
and readmission, and these frequent exacerbations may have considerable impact on
quality of life and activities of daily living (2). Strategies to reduce exacerbation
frequency are urgently required and depend on an understanding of the etiological
factors associated with exacerbations. COPD exacerbations are caused by a variety
of factors such as viruses, bacteria, and possibly common pollutants (Fig. 1).
