• COPD mechanisms
• ambulatory oxygen therapy
• assisted ventilation
• COPD epidemiology
• COPD exacerbations
• COPD pharmacology
• long term oxygen therapy
• short burst oxygen therapy
• clinical epidemiology

Exacerbations of chronic obstructive pulmonary disease (COPD) are episodes of respiratory symptom worsening that are usually associated with infective triggers and variable amounts of airway and systemic inflammation.1 There has been much interest in COPD exacerbations as they lead to considerable morbidity, hospital admission and readmission and mortality. COPD exacerbations are the most important determinants of health status in COPD2 and are important targets for therapies both from the point of view of treating the event and prevention.

It is now known from a number of studies that COPD exacerbations affect disease progression3 ,4 and have an effect on accelerating forced expiratory volume in 1 s decline independent of cigarette smoking. Some patients with COPD across disease severities are particularly susceptible to exacerbations and are known as frequent exacerbators2 ,5 and these patients are at a greater risk of poor health status, faster disease progression and mortality. The best predictor of a subsequent exacerbation and hospital admission is a history of previous exacerbations.2 ,5 Thus, it is important to understand the natural history of exacerbations and especially how severe exacerbations evolve as these are associated with significant healthcare cost.

Most studies of the epidemiology of COPD exacerbations …