Patients in whom an initial diagnosis of an AECOPD is revised to an alternative at a later phase of the study.

Patients who have a predominant history of asthma

Patients with a confirmed active malignancy

Patients who have a predominant history of bronchiectasis.

Cognitive impairment patients with a Mental Test Score (MTS) of 6 or less.

Inability to give informed consent to take part in the study

Mechanisms of COPD Exacerbation Recurrence