Introduction
Asthma affects over 25 million people in the United States. Many asthma phenotypes exist, but one of the most common types is allergic asthma.1 Around 60% of people with asthma have allergic asthma, which is defined as presenting symptoms upon exposure to an allergen.1,2 Allergic asthma is the most easily recognized phenotype, and it often begins in childhood.3
Etiology
A family history of allergic diseases like eczema, allergic rhinitis, or food or drug allergy is usually associated with allergic asthma, but a combination of genetic and environmental factors likely contribute to its development.3,4 Possible triggers of allergic asthma include dander, pollen, mold, and dust mites.5 Over 100 genes may be related to allergic asthma, many of which are involved in the body’s immune response. However, the condition does not always develop if a person has a variation in one of the allergic asthma-associated genes. Exposure to certain environmental factors can trigger epigenetic changes to the DNA, which modifies the DNA and regulates protein production. This influences allergy development in susceptible individuals.4
A balance between type 1 and type 2 immune reactions is usually present in the body, but in individuals with allergic asthma, type 2 reactions predominately occur. With type 2 reactions, the body responds to allergens by releasing immunoglobulin E (IgE).4 Upon subsequent exposures to the allergen, the body will release IgE specific to that antigen triggering inflammation of the airways in the lungs, causing an asthma attack to occur.1,4
Screening and Diagnosis
To diagnose allergic asthma, clinicians must first identify the allergen that is causing the symptoms; they do this through blood and/or skin tests. During a skin test, a clinician applies the allergens to the skin and examines the subsequent reactions. An inhaled allergen can also trigger symptoms. If this is the case, the patient should keep track of the events leading up to an asthma attack in a written journal they can then share with their clinician.5
With allergic asthma, clinicians must differentially diagnose asthma from other conditions that mimic asthma symptoms.6 Tests used to diagnose asthma include spirometry, exhaled nitric oxide (FeNO test), and bronchoprovocation. Spirometry involves an individual taking a deep breath and exhaling into a tube connected to a computer that collects information about the individual’s airflow. Adding a bronchodilator to a spirometry test examines how well airways relax before and after medication administration. A FeNO test determines the amount of nitric oxide exhaled and is generally used in milder cases of allergic asthma. A bronchoprovocation test is similar to allergy tests in that allergens are exposed to an individual’s skin and resulting reactions are noted.5
Treatment
Treating allergic asthma begins by identifying the cause of the symptoms and an asthma diagnosis. Clinicians help individuals learn how to identify triggers and avoid them, find the best medication, and develop the best action plan.5 The National Asthma Education and Prevention Program (NAEPP) 2020 focused updates to asthma management guidelines recommend that patients who are exposed and allergic to an allergen use multiple strategies to reduce allergen exposure including immunotherapy, fractional excretion of nitric oxide (FeNO), bronchial thermoplasty, and long-acting muscarinic agents.2
For patients with seasonal allergic asthma and no interval asthma symptoms, the Global Initiative for Asthma (GINA) recommends that regular daily inhaled corticosteroids (ICS) or as-needed ICS-formoterol are started immediately when symptoms begin and continued for 4 weeks after the relevant pollen season ends.3
In individuals aged 5 years and older with mild to moderate allergic asthma, the NAEPP 2020 updates recommend subcutaneous immunotherapy use as an adjunct treatment to standard pharmacotherapy in individuals whose asthma is controlled at the initiation, build-up, and maintenance phases of immunotherapy. In individuals with persistent allergic asthma, the NAEPP recommends against the use of sublingual immunotherapy in asthma treatment.2
The NAEPP also provides recommendations for indoor allergen mitigation with the goal of decreasing an individual’s exposure to allergens. Intervention plans can have single or multiple components. A mitigation strategy targeted at one or more specific allergens that an individual is both exposed and sensitized to is involved in a single-component intervention. For example, in individuals with asthma who have sensitization or symptoms related to exposure to dust mites, the NAEPP recommends reducing exposure by using impermeable pillow/mattress covers as part of a multicomponent allergen mitigation intervention.2 A multicomponent allergen mitigation intervention involves using two or more single-component interventions targeted at a specific allergen simultaneously. Largely, allergen mitigation plans involve removal of the allergen that the individual is both exposed and sensitized.2
Management and Multidisciplinary Approach
The goal of allergic asthma management is to control symptoms and reduce impairment. Achieving this goal is possible through a multidisciplinary approach including medication, allergen avoidance, and patient self-management and monitoring of symptoms to adjust therapy accordingly. Asthma control works the best when treatment and prevention is communicated between an interprofessional team of clinicians, pharmacists, and specialized nurses. Allergists and primary care physicians can aid in the diagnosis of asthma and identification of allergen triggers. Specialty nurses help with educating the patient on proper treatment use and aid in identifying the proper prescription for each patient for the best treatment compliance.7
Conclusion
Allergic asthma is the most common form of asthma. Working together, clinicians and patients can control allergic asthma with a proper diagnosis and identification of allergen triggers along with patient adherence to treatment plans. Thorough communication with healthcare teams is essential for developing a personalized treatment plan so symptoms are managed appropriately.
References
1. Asthma and Allergy Foundation of America. Allergic Asthma. Accessed April 26, 2022. https://www.aafa.org/allergic-asthma/
2. Cloutier MM, Baptist AP, Blake KV, et al. 2020 Focused Updates to the Asthma Management Guidelines: A Report from the National Asthma Education and Prevention Program Coordinating Committee Expert Panel Working Group. Journal of Allergy and Clinical Immunology. 2020;146(6):1217-1270. doi:10.1016/j.jaci.2020.10.003
3. Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention, 2021.; 2021. Accessed April 27, 2022. www.ginasthma.com
4. MedlinePlus. Allergic asthma: MedlinePlus Genetics. Accessed April 26, 2022. https://medlineplus.gov/genetics/condition/allergic-asthma/
5. Cleveland Clinic. Allergic Asthma: Causes, Symptoms, Tests & Treatment. Accessed April 27, 2022. https://my.clevelandclinic.org/health/diseases/21461-allergic-asthma
6. Medscape. Allergic and Environmental Asthma: Overview, Patient History, Differential Diagnosis. Accessed April 27, 2022. https://emedicine.medscape.com/article/137501-overview#a3
7. Chabra R, Gupta M. Allergic And Environmental Induced Asthma. In: StatPearls. StatPearls Publishing; 2022. Accessed April 28, 2022. http://www.ncbi.nlm.nih.gov/books/NBK526018/