Severe asthma: definition, diagnosis and management

In 1999 and in 2000, the first definitions of severe/refractory asthma were published.^[1],[2] Fourteen years later, the first ERS/ATS guidance on severe asthma was published, recognising there was a significant unmet need to improve the lives of people diagnosed with this condition.^[3]

The ERS/ATS guidance recommended that the first steps in treatment was to confirm the diagnosis and address any comorbidities that could be adding to the symptom burden.^[3]  It also recognised severe asthma is a heterogeneous condition consisting of several phenotypes such as eosinophilic asthma.^[3]

The 2014 ERS/ATS guidance is relatively similar to the 2023 Global Initiative for Asthma (GINA) definition.^[4]

The 2023 GINA guidance also reminds us that confirmation of the diagnosis is important, as in a study around 12-50% of people assumed to have severe asthma had an incorrect diagnosis.^[4]

A serious type of asthma

Severe asthma affects approximately 5–10% of patients with asthma and 17–34 million people globally.^[5] There may be others that are suffering the significant symptom burden who have not been considered or referred to specialist centres.^[6]

One study found that severe asthma was related to age >50 years, nasal polyposis, decreased FEV₁, not fully reversible airway obstruction, sensitisation to aspergillus, elevated neutrophils and partly to eosinophils, and tended to be more common in women.^[7]

GINA reminds us that asthma is not regarded as severe if it markedly improves when we address contributory factors such as inhaler technique and adherence.^[4] This remains the cornerstone of asthma treatment.

For the person with severe asthma, despite optimal inhaled therapies, the treatment often brings significant side effects such as obesity, diabetes, osteoporosis and subsequent fracture, increased infection risk, cataracts hypertension, sleep disturbance and psychological problems.^[4]

Biologic therapies

Biologic therapies target specific inflammatory markers and have been found to reduce the symptoms of asthma, improve lung function, and improve quality of life. They are not a panacea for severe asthma and they work on type two inflammation in asthma.^[8],[9]

 The introduction of biologic therapies to the available treatments for asthma has been a gamechanger in terms of the improvements in asthma control and more importantly on the significant morbidity and impact on the lives of those diagnosed with severe asthma.^[10]

Nevertheless, they are not a magic answer to addressing the basic issues of incorrect diagnosis, poor inhaler technique and non-adherence to standard therapies, the basics of all asthma management.

It is hoped that in the future, coordinated research efforts will improve phenotyping, allowing for safe and effective biomarker-driven approaches to severe asthma therapy.

This recognises that asthma is a diverse disease and that different people will have different phenotypes and subsequent responses to treatment. The burden on the individual with severe asthma in terms of symptoms, exacerbations and medicine side effects means that we need to be aware of it and to act.

For those of us working with all people with asthma, it is important that we get the initial diagnosis right, treat any confounding comorbidities, and refer on when we recognise that we are not getting control with standard treatments.

Any advice given and opinions expressed in this article are those of the author and do not reflect the view of Chiesi Limited (Chiesi).  All content in this article is for informational and educational purposes only.  Although Chiesi strives to always provide accurate information, it is not responsible for and does not verify for accuracy any of the information contained within.

[1] Proceedings of the ATS workshop on refractory asthma: current understanding, recommendations, and unanswered questions. American Thoracic Society. Am J Respir Crit Care Med. 2000; 162(6): 2341-2351

[2] Chung KF, Godard P, Adelroth E, et al. Difficult/therapy-resistant asthma: the need for an integrated approach to define clinical phenotypes, evaluate risk factors, understand pathophysiology and find novel therapies. ERS Task Force on Difficult/Therapy-Resistant Asthma. European Respiratory Society. Eur Respir J. 1999; 13(5): 1198-1208

^[3] Chung KF, Wenzel SE, Brozek JL, et al. International ERS/ATS guidelines on definition, evaluation and treatment of severe asthma. Eur Respir J. 2014; 43(2): 343-373

[4] GINA . Difficult-to-treat & Severe Asthma. In adolescents and Adult Patients. Diagnosis and Management. V4.0 August 2023. Available at: https://ginasthma.org/severeasthma/

[5] Menzies-Gow A, Jackson DJ, Al-Ahmad M, et al. A Renewed Charter: Key Principles to Improve Patient Care in Severe Asthma. Adv Ther. 2022; 39(12): 5307-5326

[6] Menzies-Gow A, Canonica GW, Winders TA, et al. A Charter to Improve Patient Care in Severe Asthma. Adv Ther. 2018; 35(10): 1485-1496

[7] Backman H, Jansson S-A, Stridsman C, et al. Severe asthma among adults: Prevalence and clinical characteristics. Eur Respir J. 2018; 52: Suppl, 62

[8] Shah PA, Brightling C. Biologics for severe asthma-Which, when and why?. Respirology. 2023; 28(8): 709-721

[9] Jin HJ. Biological treatments for severe asthma. Yeungnam Univ J Med. 2020; 37(4): 262-268

[10] McGregor MC, Krings JG, Nair P, et al. Role of Biologics in Asthma. Am J Respir Crit Care Med. 2019; 199(4): 433-445