Acute exacerbations are common in all levels of disease severity, and the frequency of previous admissions is a good guide to future risk. Exacerbations range from minor self treated events to hospitalisation.

An event in the natural course of the disease characterised by a change in the patient’s baseline dyspnoea, cough, and/or sputum that is beyond normal day-to-day variations, is acute in onset, and may warrant a change in regular medication in a patient with underlying COPD