Differential diagnosis of allergic versus non-allergic asthma is typically made on the basis of sensitization to allergens, such that absence of sensitization could result in a patient being managed as having non-allergic asthma. The IDENTIFY project aimed to gain data on sensitizations toward aeroallergens in patients with severe asthma who had tested negative to perennial aeroallergens in previous tests. Researchers found, patients being managed as having non-allergic asthma, a high proportion tested positive to a broad panel of aeroallergens. A diagnosis of allergic asthma therefore cannot be excluded purely on the basis of standard aeroallergen panels.

Patients were tested for sensitization to a panel of 35 perennial aeroallergens, with positive sensitization indicated by CAP ≥ 0.35 kU/L. There were 454 patients with complete and valid data that had previously tested negative to perennial aeroallergens. Overall, 43.6% of the analyzed patients tested positive for at least one of the included aeroallergens, with 18.7% testing positive for three or more, and 4.2% positive for more than 10. The most common sensitizations were to Staphylococcus aureus enterotoxin B, Aspergillus fumigatus, Candida albicans, Dermatophagoides farinae, and Rhizopus nigricans, each of which tested positive in at least 9.7% of the population.

Koschel D, Mailänder C, Schwab Sauerbeck I, Schreiber J. Non-allergic severe asthma: is it really always non-allergic? The IDENTIFY project. Allergy Asthma Clin Immunol. 2020 Nov 2;16(1):92. doi: 10.1186/s13223-020-00489-z. PMID: 33292478; PMCID: PMC7607813.