Question
What is eosinophilic asthma, and how does it differ from other forms of asthma?
Answer
- A common type of severe asthma driven by an increased number of eosinophils.
- Increased eosinophils causes airway inflammation that can lead to asthma symptoms.
- Dyspnea, wheezing, fever, and blood-tinged sputum containing eosinophil-derived Charcot-Leyden crystals may also be present.
Eosinophilic asthma is a prevalent form of severe asthma characterized by an elevated eosinophil count. When these eosinophils become activated, bearing in mind their primary presence in tissues, they induce airway remodeling and inflammation. Consequently, the greater the number of activated eosinophils, the more pronounced the airway inflammation, leading to typical asthma symptoms such as coughing, wheezing, and shortness of breath.
Asthma associated with eosinophilia is typically categorized as mild to moderate, with eosinophils in the blood measuring less than 1,500 microliters. However, if a patient's eosinophil count exceeds 1,500 microliters upon blood analysis, it should raise concerns about other eosinophilic pulmonary conditions, such as allergic bronchopulmonary aspergillosis. This possibility should be taken into account.
Eosinophils not only contribute to inflammation and asthma but can also affect other allergic disorders, including allergic rhinitis and atopic dermatitis. All these conditions are linked to an increased number of eosinophils. Consequently, considering eosinophil levels in a complete blood count (CBC) is vital. In the case of individuals with hypereosinophilic adult-onset asthma, the severity of their condition may require systemic glucocorticosteroids to control inflammation, particularly in the early stages of the disease.
Research indicates that hypereosinophilic adult-onset asthma is often associated with severe sinus disease, nasal polyposis, and, in some cases, aspirin-exacerbated respiratory disease. This emphasizes the importance of considering comorbidities when treating asthma. Addressing these additional conditions is essential, as asthma should not be viewed as a standalone disease. For patients with eosinophilic asthma, assessing and managing comorbidities like severe sinus disease, GERD, nasal polyps, and aspirin sensitivity become crucial aspects of their overall care.
This Ask the Expert is an edited excerpt from the course, Objective Measures of Asthma, presented by Kevin Collins, PhD, RRT, RPFT, AE-C.
