Severe asthma is defined as asthma that is uncontrolled despite adherence with optimised ICS-LABA therapy and treatment of contributory factors, or that worsens when high-dose treatment is decreased.26


Difficult-to-treat asthma is defined as asthma that remains uncontrolled despite prescribing medium or high dose ICS-LABA treatment or requires high dose ICS-LABA treatments to maintain good symptom control and reduce exacerbations.

 

  • Poorly controlled and/or unrecognised severe asthma is a significant problem, leading to morbidity and mortality. 
  • Severe asthma is associated with poor asthma control, impaired lung function and repeat exposure to oral corticosteroids (OCS) which can lead to further OCS-related adverse effects such as diabetes, adrenal insufficiency, and osteoporosis.
  • Severe asthma is estimated to affect 3% to 5% of the asthma population.
  • Scotland has higher rates of difficult and severe asthma compared to the rest of the UK.37
  • Proxy measures of inhaled high dose corticosteroids (ICS) or number of courses of oral corticosteroids (OCS) treatments have been suggested as indicators of those at risk of severe asthma.37
  • The figure below outlines the differences in difficult or severe asthma prevalence, based on the indicators of high-dose ICS or those receiving three or more OCS courses across the nations in the UK in 2016.37
  • For three or more OCS prescriptions Scotland has the highest figure in the UK, with 4.3%, compared to the UK figure of 3.4% of the asthma population.

 

Prevalence levels of severe asthma in the UK (2016)

Early identification of at-risk patients with asthma is key to ensure prompt referral to specialists for consideration of Monoclonal antibody (mAb) therapy where appropriate. Pathways have been developed to support the identification and management of patients at risk of severe asthma.38