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Allergic Asthma
Learning objectives
By the end of this chapter, participants will be able to:
recall the importance of identifying asthma-triggers for optimal patient management
describe the evidence on the reduction of allergen exposure in reducing exacerbations in sensitised asthmatic patients.
Asthma
Asthma is a heterogenous disease, characterised by airway inflammation, variable expiratory airflow limitation and the presence of respiratory symptoms which vary in severity and frequency.1
It is estimated that 70 million EU citizens suffer from asthma.2
Genetic predisposition to developing IgE mediated sensitivity (also referred to as atopy) is the strongest factor associated to the development of asthma.3,4 However, other factors, such as viral respiratory infections, may also contribute to the development of asthma.4
Up to 90% of children and 60% of adults with asthma have allergic triggers.5,6
Common allergic triggers of asthma
Several allergen sources associated with asthma:
Not all asthma symptoms are triggered by allergies
Clinical symptoms of asthma
Most common symptoms of asthma:1
Not all patients will experience all of the mentioned respiratory symptoms and some may also experience other symptoms, i.e. gastrointestinal complaints in children.15 Patterns of these symptoms can be due to allergen exposure.3
Allergic asthma is often part of the ‘atopic march’ and can develop in patients with atopic dermatitis and allergic rhinitis.16
> 80% of asthmatics have co-morbid rhinitis (allergic or non-allergic) which is often underdiagnosed.17,18
Therefore, patients with allergic asthma may also display symptoms of other atopic conditions, such as nasal congestions, persistent nasal discharges, dry skin and food related symptoms.19
In allergy-triggered asthma, what should physicians consider within the patient’s medical history and when selecting appropriate diagnostic tests?
Asthma diagnosis and management19–22
Following an accurate asthma diagnosis, the investigation of the asthma phenotype includes evidence of sensitisation to a specific allergen:
During allergy-triggered asthma diagnosis, when should a primary care physician refer patient to an allergy specialist?
Management of asthma
All patients should be provided with a personalised written asthma action plan appropriate for their level of asthma control and health literacy.21 A written asthma action plan should include:
The patient’s usual asthma medications21
When and how to increase medications, including oral corticosteroids21
How to access medical care if symptoms fail to respond21
Individual allergens and irritants that worsen the patient’s asthma23
Why is it important to confirm triggers in asthma?
A diagnosis of asthma with confirmation of the correct triggering allergy can provide patients with the most effective therapeutic strategies. This may involve allergen avoidance,25 pharmacotherapy,26 allergen immunotherapy29,30 and patient education.19 This, in turn, can:
prevent potential fatalities
Patients with asthma and food allergies are more likely to have severe asthma exacerbations in comparison to asthmatics with no food allergy.31
improve the patient’s quality of life and prevent unnecessary avoidance measures
For example, a common trigger of allergic asthma are pets. It may be recommended for the household to remove the pet but studies have shown that the loss can have a significant impact on the child’s wellbeing, so careful consideration is advised.32,33
reduce costs on unnecessary treatments
Specific IgE testing with respiratory and/or skin problems in primary care may reduce the overall costs to society by reducing the use of ineffective medications.34
Potential uses of component-resolved diagnostics (CRD)
Various allergen components associated to asthma are available for component-resolved diagnostics. These include allergen components from house dust mites, furry animals and several types of pollen.
Studies have explored the use of component-resolved diagnostics (CRD) as a tool to support the diagnosis and management for asthma. For example, in furry animals:
CRD was used to explore the pattern of sensitisation in patients with severe and controlled asthma to cats, dogs and horses. It was shown that children with problematic severe asthma had higher IgE levels and were more likely to have triple sensitisation to these animals.32
Sensitisation to the allergen component Fel d 1 (cat) shown to be a risk factor for asthma in cat-allergic children.36
All components selected and results obtained using component-resolved diagnosis should be interpreted on the patient’s previous diagnostic tests, medical history and relevant symptoms.20
Summary
Allergy is the most common trigger in asthma.
Common allergic triggers include house dust mites, cats, dogs, moulds, tree and grass pollens.
Allergen sensitisation testing in primary care can be carried out using in vitro diagnostic tests.
Written asthma action plans with advice on pre-identified trigger exposure reductions are recommended for asthmatic patients:
Exposure reductions are effective in reducing severe asthma exacerbations requiring hospital attendance – this may be beneficial in patients who are at higher risk of exacerbation due to viral infection.
Long-term exposure reduction strategies can reduce the need for medication.
Common triggering allergens in asthma are also available for CRD testing.9
References
Global Initiative for Asthma. https://ginasthma.org/wp-content/uploads/2018/04/wms-GINA-2018-report-V1.3-002.pdf [accessed May 2019].
European Academy of Allergy and Clinical Immunology. https://www.eaaci.org/images/media/EAACI_Manifesto_brochure_Interactive.pdf [accessed May 2019].
Ali FR. Clinical Medicine. 2011;11(4):376–80.
Pawankar R, et al. (Editors). WAO White Book on Allergy. 2011. Wisconsin: World Allergy Organization.
Allen-Ramey F et al. J Am Board Fam Pract. 2005;18(5):434–9.
Høst A, Halken S. Allergy. 2000;55(7):600–8.
Suphioglu C et al. Lancet. 1992;339(8793):569–72.
D’Amato G et al. Allergy. 2007;62(1):11–6.
Noertjojo K et al. J Allergy Clin Immunol. 1999;103(1):60–5.
O‘Driscoll BR et al. Clin Exp Allergy. 2009;39(11):1677–83.
Roberts G et al. J Allergy Clin Immunol. 2003;112(1):168–74.
Caffarelli C et al. Arch Dis Child. 2000;82(2):131–5.
Zheng T et al. Allergy Asthma Immunol Res. 2011;3(2):67–73.
Bosquet J et al. Allergy. 2008:63(Suppl. 86):8–160.
Jacobs TS et al. J Allergy Clin Immunol. 2014;134(3):737–9.
Bacharier LB et al. Allergy. 2008: 63(1): 5–34.
Portnoy JM. Mo Med. 2011;108(5):339–43.
Global Initiative for Asthma. https://ginasthma.org/wp-content/uploads/2019/04/GINA-2019-main-Pocket-Guide-wms.pdf (accessed May 2019).
National Institute for Health and Care Excellence. https://cks.nice.org.uk/asthma (accessed May 2019).
National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health-pro/resources/lung/naci/discover/environmental-exposure.htm (accessed May 2019).
Murray CS et al. Am J Respir Crit Care Med. 2017;196(2):150–8.
Morgan WJ et al. N Engl J Med. 2004;351(11):1068–80.
Murray CS et al. Thorax. 2006;61(5):376–82.
Halken S et al. J Allergy Clin Immunol. 2003;111(1):169–76.
Novartis Pharmaceuticals Ltd. https://www.medicines.org.uk/emc/product/5327/smpc (accessed May 2019).
Abramson MJ et al. Cochrane Database Syst Rev. 2010;(8):CD001186.
Dhami S et al. Allergy. 2017;72(12):1825–48.
Liu A et al. J Allergy Clin Immunol. 2010;126(4):798–806.
Coker TR et al. Arch Pediatr Adolesc Med. 2011;165(4):354–9.
Konradsen JR et al. Pediatr Allergy Immunol. 2014;25(2):187–92.
Zethraeus N et al. Italian Journal of Pediatrics. 2010;36:61.
Smith HE et al. J Allergy Clin Immunol. 2009;123(3):646–50.
Grönlund H et al. Clin Exp Allergy. 2008;38(4):1275–81.
