Abstract
BackgroundThis differential diagnosis of allergic vs 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. In Germany, the number of specific allergen tests is limited and non-standardized (across clinicians and laboratories), with the potential for false negative diagnoses. IDENTIFY aimed to gain data on sensitizations toward aeroallergens in patients with severe asthma who had tested negative to perennial aeroallergens in previous tests.MethodsThis was a single visit, non-randomized, non-interventional study conducted in 87 centers across Germany. The only inclusion criteria were that patients had to be adults (at least 18 years of age) with a diagnosis of severe asthma (receiving at least Global Initiative for Asthma Step IV therapy), and who had previously tested negative to perennial aeroallergens. Patients were then tested for sensitization to a panel of 35 perennial aeroallergens, with positive sensitization indicated by CAP ≥ 0.35 kU/L.ResultsOf 588 patients recruited, 454 had complete and valid data, and 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 ten. The five 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.ConclusionsIn this group of patients being managed as having non-allergic asthma (and who had all previously tested negative to perennial aeroallergens), 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.
Highlights
This differential diagnosis of allergic vs 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 nonallergic asthma
The aim of the current study (IDENTIFY) was to gain data on sensitizations toward aeroallergens in patients with severe asthma who had tested negative to perennial aeroallergens in previous tests—i.e., patients being managed in clinical practice as not being indicated anti-immunoglobulin E (IgE) therapy for allergic asthma
The only inclusion criteria applied were that patients had to be adults with a diagnosis of severe asthma, and who had previously tested negative to perennial aeroallergens in skin prick tests, radioallergosorbent test (RAST), or both
Summary
This differential diagnosis of allergic vs 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 nonallergic asthma. With the increasing numbers of biologic therapies available for the management of severe asthma, accurate differential diagnosis of allergic and non-allergic asthma is becoming increasingly important. This differential diagnosis is typically made on the basis of the presence or absence of sensitization to allergens, with eligibility. There is frequently no clear rationale to the selection of these eight aeroallergens, and importantly the panel is not standardized across physicians or laboratories This limited and non-standardized testing has the potential for false negative diagnoses— in other words indicating the absence of sensitization
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