Background: The asthmatic-prodromal phase of Churg–Strauss syndrome (CSS) is usually considered allergic, but data about the involved allergens are scarce. The aim of our work was to examine the prevalence of allergy in a group of CSS patients and in two control groups of persistent asthmatic subjects selected for eosinophilia >10% [first control group patients (CGP1)] and eosinophils <6% [second control group patients (CGP2)].
Methods: The respiratory symptoms, and the results of prick test and/or RAST for the common allergens, performed before the vasculitic phase in 51 CSS, were retrospectively evaluated and compared with those of 46 CGP1 and 50 CGP2.
Results: 31.4% of CSS vs 67.4% of CGP1 (P = 0.0004) and vs 58.0% CGP2 (P = 0.007) were allergic. The number of subjects with seasonal allergies was lower in CSS vs CGP1 (P = 0.0069) and vs CGP2 (P = 0.0002). The number of perennial allergies was significantly higher in CSS than in both control groups (CSS vs CGP1, P = 0.0108; CSS vs CGP2, P = 0.0079). The subjects allergic to Dermatophagoides were prevalent in CSS vs CGP1 (P = 0.0045) but not vs CGP2.
Conclusions: The evidence of allergy, considered as the demonstration of specific IgE consistent with the clinical history, is present in less than one-third of CSS and the higher prevalence of seasonal allergies in the controls disagrees with persistent asthma. Allergy may be only one of several mechanisms triggering exacerbation of asthma or supporting chronic airway inflammation as in asthma in general. Alternatively, unidentified allergens may play a role.