The natural history of chronic obstructive pulmonary disease (COPD) is one of a progressive lung function reduction, essentially expressed by an accelerated decline in forced expiratory volume in one second (FEV1), with limited exercise activity, poor health status and systemic (extrapulmonary) effects, all interspersed with a varying frequency of episodes of COPD exacerbation. Frequency of COPD exacerbations increases with increased disease severity, mostly in patients with advanced COPD (FEV1 <50% predicted), who are often prone to frequent and repeated episodes.
COPD exacerbations have a serious impact on patients in terms of lung function decline or disease progression, morbidity and mortality, and poor quality of life, and involve huge economic costs. A background of lower FEV1 and frequent COPD exacerbations, defined as at least three episodes over the previous year within a geographic area 1, are considered vital risk factors for hospitalisation for a COPD exacerbation. Episodes of COPD exacerbation most commonly result in more severe airflow obstruction, with gas exchange 2 and pulmonary haemodynamic worsening 3, the latter being also predictive of hospitalisation for these exacerbations. Prognosis following severe hospitalised COPD exacerbation is also very poor, with high mortality rates at 2 yrs 4. According to the World Health Organization, COPD deaths are set to increase to ∼5 million annually, making this the fifth leading cause of global mortality 5. Moreover, the socio-economic burden to the different healthcare services is dramatic. While a global survey estimated considerable annual direct costs 6, hospital admissions for COPD exacerbation increase the economic burden 7. Altogether, COPD exacerbations represent one of the major battle fields of the physicians' clinical load, who in addition have access to a limited therapeutic armamentarium.
In the current issue of the European Respiratory Journal, new evidence of the complex interaction …