What are the key diagnostic criteria for Allergic Bronchopulmonary Aspergillosis (ABPA) in patients with asthma?

Allergic Bronchopulmonary Aspergillosis (ABPA) in patients with asthma is diagnosed based on a combination of clinical, immunological, and radiological criteria. Key diagnostic criteria include the presence of asthma, immediate cutaneous reactivity to Aspergillus antigens or elevated Aspergillus-specific IgE, elevated total serum IgE levels, peripheral blood eosinophilia, and radiological evidence of bronchiectasis or fleeting pulmonary infiltrates. Additionally, serum precipitins to Aspergillus and elevated Aspergillus-specific IgG may support the diagnosis. The diagnosis requires exclusion of other causes of bronchiectasis and pulmonary infiltrates. These criteria reflect an allergic hypersensitivity reaction to Aspergillus colonization in the airways of asthmatic patients, leading to airway inflammation and damage Patterson & Strek 2010Greenberger et al. 2014Roboubi et al. 2023.

While UK asthma guidelines NICE NG245 do not explicitly detail ABPA diagnostic criteria, they emphasize the importance of identifying sensitization to allergens such as Aspergillus in patients with difficult-to-control asthma, including raised total IgE and eosinophilia as markers of allergic inflammation. In clinical practice, suspicion of ABPA should arise in asthmatic patients with recurrent exacerbations, high total IgE (>1000 IU/mL), positive Aspergillus-specific IgE, and characteristic radiological findings such as central bronchiectasis. Confirmatory diagnosis often involves multidisciplinary assessment including immunological testing and high-resolution CT scanning Patterson & Strek 2010Roboubi et al. 2023.

In summary, the key diagnostic criteria for ABPA in asthma patients are:

• Clinical history of asthma with recurrent exacerbations and poorly controlled symptoms despite standard therapy NICE NG245
• Immediate hypersensitivity to Aspergillus antigens demonstrated by skin prick test or elevated Aspergillus-specific IgE Greenberger et al. 2014
• Elevated total serum IgE, typically >1000 IU/mL Roboubi et al. 2023
• Peripheral blood eosinophilia Patterson & Strek 2010
• Radiological evidence of central bronchiectasis or transient pulmonary infiltrates Roboubi et al. 2023
• Presence of serum precipitins or elevated Aspergillus-specific IgG antibodies Greenberger et al. 2014

These integrated criteria guide clinicians in differentiating ABPA from other causes of asthma exacerbations and bronchiectasis, facilitating timely diagnosis and management.