Defining control and severity
Control and severity are separate issues
Asthma control and severity are separate issues and should not be confused when defining severe asthma. Control while on medication is used as an indication of severity level, since responsiveness to treatment is a measurement of disease severity. 1The ERS/ATS Task Force indicates that an individual may have severe asthma, yet be well controlled on an aggressive medical regimen. 2In other words, patients with severe asthma can have good control – meaning that symptoms and exacerbations are minimised – while patients with mild asthma can have poor control because symptoms and exacerbations are not being kept in check. 2
Both the GINA guidelines and ERS/ATS Task Force approaches to asthma severity levels are based on response to medication. 1-2 It assumes that patient adherence is maximised and modifiable risk factors and comorbidities have been treated. Control should be continuously reassessed and medication adjusted up or down as necessary, with the consideration that severe asthma requires high-level medication to maintain control and, in some cases, may not achieve full control at all. 1-2
“Asthma control is the extent to which the manifestations of asthma can be observed in the patient, or have been reduced or removed by the treatment.”
GINA 2016. 1
Uncontrolled asthma is defined as at least one of the following: 2
- Poor symptom control: ACQ result consistently >1.5, ACT result <20 (or ‘not well controlled)
- Frequent severe exacerbations: Two or more bursts of systemic corticosteroids (>3 days each) in the previous year
- Serious exacerbations: Exacerbation requiring at least one hospitalisation, intensive care stay or mechanical ventilation in the previous year
- Airflow limitation: FEV1 <80% predicted (in the face of reduced FEV1/FVC, defined as less than the lower limit of normal) after withholding bronchodilators for an appropriate period of time
Control is independent of severity level. Mild asthma can be poorly controlled, and severe asthma can be well controlled. 1Degree of control can be used to determine whether treatment adjustments are required, 3by assessing two domains: 1
- Symptom control
- Future risk of adverse events
Future risk can be partly predicted by symptom control, but future risk of adverse events can be independent of symptom control. 3
‘Severity’ has been used to describe the underlying nature or intensity of asthma in the absence of treatment which is important problem in areas of the world with limited access to asthma therapies. 24Recent definitions of severity focus on disease that is refractory or insensitive to currently available medications, including corticosteroids. 25
Guidelines define severe asthma as:
GINA 2016 1
ERS/ATS Task Force 2
Asthma that requires Step 4 or 5 treatment (high-dose ICS plus at least one other controller and in some cases OCS and/or other add-on therapy) to maintain symptom control
Asthma which requires treatment with high dose ICS plus a second controller (and/or systemic corticosteroids) to prevent it from becoming ‘uncontrolled’ or which remains ‘uncontrolled’ despite this therapy
ATS, American Thoracic Society; ERS, European Respiratory Society; GINA, Global Initiative for Asthma; ICS, inhaled corticosteroids; OCS, oral corticosteroids.
The 2016 GINA guideline update recommends assessing asthma severity retrospectively from the level of treatment required to control symptoms and exacerbations. It should also be reassessed when optimal control is achieved and maintained. 1This differs from previous GINA definitions, which subdivided asthma by severity based on the level of symptoms, airflow limitation and lung function variability. 16
Asthma severity classification
Refer for add-on treatment, e.g. tiotropium, omalizumab, mepolizumab
|Other optional controllers||
Low-dose ICS + LTRA
High-dose ICS + LTRA
As-needed SABA or low-dose ICS/formoterol
ICS, inhaled corticosteroids; IgE, immunoglobulin E; LABA, long-acting beta-agonist; LTRA, leukotriene receptor antagonist; OCS, oral corticosteroids; SABA, short-acting beta-agonist.
Adapted from GINA 2016. 1
Exacerbations as a severity measure
An asthma exacerbation is an acute or subacute episode when asthma symptoms progressively worsen. Exacerbation symptoms include shortness of breath, wheezing, cough, and chest tightness. Exacerbation frequency and seriousness are used to measure asthma severity: the ATS/ERS guidelines refer to exacerbations and the occurrence of severe or serious exacerbations as a measure of control. 12
In general, more frequent and severe exacerbations indicate greater underlying disease severity. 78While exacerbations are episodic, chronic inflammation is usually present. 1Both exacerbations and inflammation may fluctuate over time, in any severity category. 78
What is the relationship between control, severity and exacerbations?
In some cases, asthma symptoms can be adequately controlled by medication. However, severe asthma is often uncontrolled. 2Poor control is associated with future exacerbations and progressive decline in lung function. 8However, good symptom control does not eliminate exacerbation risk. 3
Patients with ‘good’ symptom control may still be at risk of exacerbations
Schematic illustrating the risk of asthma exacerbation in patient populations with good, partial and poor asthma control. 3
Reprinted by permission from Macmillan Publishers Ltd: Prim Care Respir J 2013;22:344–52. Copyright (2013).
Additional severe asthma characteristics are being explored as a means of subtyping patients. This may help to better predict a patient’s future course and, potentially, allow individualisation of therapeutic approach. 2
Diagnosing severe asthma
Severe asthma is commonly misdiagnosed because it can be complicated by a number of factors. Guidelines recommend the following steps to rule out these factors, before reaching a diagnosis of severe asthma: 1-2 5
- Investigate the patient’s inhaler technique and adherence to medication
- Identify and treat comorbidities such as chronic rhinosinusitis, gastroesophageal reflux disease or obstructive sleep apnoea syndrome
- Determine if severe asthma is controlled or uncontrolled
Differentiating difficult-to-treat asthma
Severe asthma is often confused with difficult-to-treat asthma, because both can be hard to control with standard asthma medications. However, there are a number of different underlying factors in difficult-to-treat asthma that, when properly addressed, can help to regain disease control. 1-2 5
“Difficult-to-treat asthma remains uncontrolled despite the prescription of high-intensity asthma medications, due to persistent poor compliance, psychosocial factors, persistent environmental exposure to allergens or toxic substances, or untreated comorbidities.”
Bel, et al. 2011. 5
Measuring asthma control
Asthma control is the extent to which the manifestations of asthma can be observed in the patient, or have been reduced or removed by the treatment. 1Clinical control is defined as absence of symptoms, no daily activity limitations or requirement for reliever medication, normal or near-normal lung function and no exacerbations. 1
The ACT is a patient-administered, five-item tool, which can help identify poorly controlled asthma if a patient scores 19 or lower. 9
The ACT quantifies asthma control by scoring patient responses to the following questions on a scale of 1–5: 9
- In the past 4 weeks, how much of the time did your asthma keep you from getting as much done at work, school or at home?
- During the past 4 weeks, how often have you had shortness of breath?
- During the past 4 weeks, how often did your asthma symptoms (wheezing, coughing, shortness of breath, chest tightness or pain) wake you up at night or earlier than usual in the morning?
- During the past 4 weeks, how often have you used your rescue inhaler or nebuliser medication (such as albuterol/salbuterol)?
- How would you rate your asthma control during the past 4 weeks?
Keeping a record of patients’ scores over time aids monitoring of long-term asthma control and promotes patient–physician discussion.
The ACT can be accessed online here.
Together with response to medication and clinical history assessment, spirometry is considered the gold standard testing method for asthma diagnosis. 1
What is the value of using alternative assessment methods?
Pathologic examination using alternative assessment methods is only performed in patients with minimal response to treatment, and can have varied success. Gaining a comprehensive view of the pathobiology of severe asthma is complicated, invasive, and rarely of additional value. Alternative methods such as lung tissue biopsy, CT scans and X-rays are seldom performed and not discussed in guidelines as diagnostic tools. 1-2
Severe asthma management guidelines
Current tests and guidelines for management and follow-up
Currently, each of the recognised international authorities provides guidance on severe asthma management. As this is still a rapidly developing area, further developments that benefit the treatment of patients with severe asthma are expected.
The most recent international guideline developments in severe asthma have stemmed from the ERS/ATS Task Force workshop in 2014. The guideline updates include ten therapeutic options for severe asthma. 2
1. In patients with mild-to-moderate asthma, exacerbations can be effectively treated with high doses of ICS
- In 30% of adult patients with severe asthma, an OCS is required in addition to ICS to maintain some degree of asthma control. Patients receiving continuous OCS, and high-dose ICS to a lesser extent, should also have their weight, blood pressure, blood glucose, eyesight and bone density measured regularly
2. High doses of ICS are generally recommended as maintenance therapy
3. Add‐on treatments (without phenotyping) include a LABA or theophylline
4. Leukotriene pathway modifiers may be used, but have not been proven as effective as combination ICS/LABA therapy in moderate asthma
5. Long‐acting muscarinic antagonists (or anticholinergics) have demonstrated improvement in patients with moderate-to-severe asthma who have not achieved control with medium‐ to high‐dose ICS alone or in combination with LABAs
6. Therapeutic trial of omalizumab is recommended in patients with severe allergic asthma
7. Methotrexate is not recommended
8. Do not use macrolide antibiotics in patients with severe asthma. This recommendation does not apply to other indications, such as treatment of bronchitis, sinusitis or other bacterial infections as indicated
9. Antifungal treatments are suggested in adults with severe asthma and recurrent allergic bronchopulmonary aspergillosis exacerbations
10. Bronchial thermoplasty recommended in adults only in institutional review board-approved independent systematic registry or clinical trial
Written asthma action plans
GINA guidelines now recommend a written action plan to help patients manage their asthma, of any severity level. 1The intent is to ensure that patients are aware of their symptoms and control, so that medication can be adjusted in the short-term if control changes. 1The overall aim is to improve disease self-management to minimise exacerbation risk and healthcare utilisation. 1
Key features of a plan include: 1
- Content and wording of an appropriate level for the patient’s health literacy and asthma control
- Explains when and how to change reliever and controller medications, including OCS
- For most patients, a short course of OCS (e.g. 40–50 mg/day for 5–7 days) is recommended for patients who:
- Fail to respond to an increase in reliever and controller medications for 2–3 days
- Deteriorate rapidly or who have a PEF or FEV1 <60% of their personal best or predicted value
- Have a history of sudden severe exacerbations
- For most patients, a short course of OCS (e.g. 40–50 mg/day for 5–7 days) is recommended for patients who:
- Explains when to access medical care if symptoms do not respond to treatment
- Patients who deteriorate quickly should be advised to go to an acute care facility or see their doctor immediately
Action plan criteria will vary between patients and the plan should be individualised. 1
- GINA 2016 © 2016 Global Initiative for Asthma, all rights reserved. Use is by express license from the owner. www.ginasthma.org (Last accessed December 2016).
- Chung KF, et al. Eur Respir J 2014;43:343–73.
- Blakey JD, et al. Prim Care Respir J 2013;22:344–52.
- Bousquet J, et al. J Allergy Clin Immunol 2010;126:926–38.
- Bel EH, et al. Thorax 2011;66:910–7.
- Nathan RA, et al. J Allergy Clin Immunol 2004;113:59–65.
- Thomas M, et al. Prim Care Respir J 2009;18:41–9.
- Trejo Bittar HE, et al. Annu Rev Pathol 2015;10:511–45.
- Asthma Control Test. Available at: http://www.asthmacontroltest.com/. Last accessed November 2016.