What is severe asthma?
Asthma which requires the use of high dose inhaled corticosteroids (ICS) plus a second controller
(and/or systemic corticosteroids) to prevent it from becoming ‘uncontrolled’ or which remains
‘uncontrolled’ despite this therapy.  (International European Respiratory Society [ERS] and American Thoracic Society [ATS] Task Force.)
Patients with refractory disease either remain uncontrolled despite their treatment being optimised or require high doses of controller and reliever medication to maintain control. 
The eosinophilic asthma phenotype has been shown to be associated with asthma severity, late-onset disease and steroid refractoriness. 
By characterising a patient’s severe asthma phenotype, they can be treated differently with personalised and targeted therapies, and outcomes could be improved. 
Prevalence and burden
Severe asthma patients are at high risk of having a severe exacerbation and are often dependent on oral corticosteroids.
Nucala is an anti-IL-5 treatment that specifically targets the eosinophilic phenotype.
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- Nucala Summary of Product Characteristics. Available from www.medicines.ie Last accessed: May 2020
- Walford H, Doherty T. J Asthma Allergy 2014;11:53–65.
Nucala is a registered trademark of the GlaxoSmithKline Group of Companies