Exacerbations of severe asthma.

Exacerbations occur frequently in severe asthma. They result in significant morbidity and can lead to hospitalization and death. Severe exacerbations can also lead to an accelerated decline in lung function. Phenotyping severe asthma can aid with both prognostication of exacerbation risk and maintenance treatment selection to minimize future risks of exacerbations in severe asthma. The rate of exacerbations differs by phenotype, and is most frequent in refractory eosinophilic asthma and early onset allergic asthma. Phenotype specific therapy can reduce exacerbations in both these forms of severe asthma. Exacerbations are multi-component events. Each exacerbation represents an opportunity to assess and target treatment to the domains of airway pharmacotherapy, self-management behaviour, risk factors, and relevant co-morbidities.