An Introduction to Severe Asthma

What is Severe Asthma?

Severe asthma refers to asthma which does not get better with the usual treatment leaving patients with breathing problems most of the time, meaning that a different treatment approach may be necessary to control the symptoms ^1,2

• ~200,000 people in the UK have severe asthma^*1,2
• 39% (61/155) of people that died from asthma were reported to have severe asthma between 2012–2013^†3
• In a UK study^‡,~93% (748/808) of severe asthma patients had a least one corticosteroid-related morbidity⁴

*Approximately 4% of the 5.4 million people in the UK who have asthma have severe asthma (approximately 200,000–250,000). GINA defines severe asthma as asthma that remains uncontrolled despite optimised treatment with high-dose ICS-LABA or that requires high-dose ICS-LABA to prevent it from becoming uncontrolled1,2,5

†In the National Review of Asthma Deaths (NRAD) (2014) sufficient data was available on 195 people who died of asthma between 2012–2013. From 195 people, 155 had their asthma severity recorded prior to death. No history of asthma was reported as 3% (4/144), mild asthma was reported as 9% (14/155), moderate asthma was reported as 49% (76/155) and severe asthma was reported as 39% (61/155). The NRAD is the first UK-wide investigation into asthma deaths that took place between Feb 2012 to Jan 2013. Experts such as general practitioners (GPs), nurses and pharmacists looked at medical records and other information relating to these deaths from doctors’ surgeries, hospitals, emergency services and coroners’ offices. Severity was defined as follows: The BTS/Scottish Intercollegiate Guidelines Network (SIGN) treatment steps 1 and 2 were used as a surrogate for mild and moderate severity; those who were prescribed four asthma medications and those who had been admitted to hospital in the past year, needed OCS daily or had two or more prescriptions for systemic corticosteroids in the past year were classified as severe.3

‡A cross-sectional observational study to determine the prevalence of systemic corticosteroid-induced morbidity in severe asthma using the Optimum Patient Care Research Database (OPCRD), (7,195 subjects in three age- and gender-matched groups) - severe asthma (GINA treatment step 5 with four or more prescriptions/year of OCS, N=808), 770 subjects with severe asthma from the BTS Difficult Asthma Registry (442 receiving daily OCS to maintain disease control). Severe asthma was defined by the Global Initiative for Asthma (GINA) treatment step 5 with four or more prescriptions/year of OCS. 770 subjects with severe asthma from the BTS Difficult Asthma Registry (442 receiving daily OCS to maintain disease control).4

Type 2 Inflammation 

No single biomarker fully captures the complexity of Type 2 inflammation in asthma^6,7

50 - 70% of adult asthma patients have Type 2 Inflammation, with close to 1 in 2 patients presenting with multiple Type 2 inflamatory biomarkers^7,8,9.

Adapted from Robinson 2017¹⁰ and Gandhi et al. 2016¹¹

Biomarkers

59% of patients with severe asthma have several elevated biomarkers¹²

Type 2 biomarkers support the assessment of type 2 inflammation^{10,11, 13}

% of patients presenting with each kind of raised biomarker¹².

Elevated EOS, FeNO, OR IgE is evidence of Type 2 Asthma⁵

88% of patients with severe asthma may have type 2 inflammation¹⁵ 

DUPIXENT (dupilumab) is shown to work in patients with severe asthma type 2 biomarkers ((EOS ≥ 150 cell/μL and/or FeNO  ≥ 25 ppb with or without elevated IgE)^5,16

Over HALF of type 2 asthma patients have more than one elevated type 2 biomarker^12,§

• Elevated EOS and FeNO are strong predictors of a good asthma response to DUPIXENT¹⁶
• Oral Corticosteriod (OCS) may suppress type 2 biomarkers, which should be accounted for when assessing type 2 asthma status in patients taking OCS ^5,17.

^§ Within the International Severe Asthma Registry (ISAR), data were analysed in adults with severe asthma with available biomarkers (n = 1,175) from 10 countries in North America, Europe, and Asia, with respecified thresholds for biomarker positivity - (serum IgE  ≥ 75 IU/mL, blood eosinophils  ≥ 300 cells/mL, and FeNO  ≥ 25 ppb); and with hierarchical cluster analysis using biomarkers as continuous variables. Distinct clusters were shown with significant overlap of biomarker positivity in severe asthma.¹²

Watch this video to learn more about Type 2 inflammation in asthma

Guidelines