D2.257 - Is It Beneficial To Expand The Allergy Test Panel Based On Component-Based Test Results In Chronic Urticaria?

Chronic urticaria (CU) is a disease associated with mast cell activation that significantly reduces quality of life. The necessity of routine allergy testing in CU and the clinical contribution of comprehensive panels are controversial.

We aimed to evaluate the diagnostic yield of comprehensive component-based IgE screening (M-CRD test, 295 allergen extract and component) in CU patients, the most common sensitization patterns, and its correlation with clinical history; and to identify candidate components for an optimized panel with high predictive value.

Data from 100 patients aged ≥18 years diagnosed with CU between August 2022 and March 2024 were retrospectively analyzed in a cross-sectional study. Serum samples were analyzed using M-CRD. Sensitization rates, the number of positive cases per patient, and the consistency between clinical history and test results were evaluated.

IgE sensitization to at least one allergen component was detected in 58% of patients, while 42% were completely negative. Of  the total 295 reagents, no positivity was observed in any patient for 169 of them; of the 126 allergens that tested positive, 70 were positive in only 1% of patients. ≤2 component positivity was found in 65% of positive cases. Positivity was most frequently observed in inhalant allergens; house dust mite (HDM) components were particularly prominent (Der p 2/Der f 2 16%, Der p 23 14%, Der p 1 13%), and at least one HDM component was positive in 21% of cases. While 76.2% of house dust-positive patients had additional allergic diseases, 58.2% of house dust-negative chronic urticaria patients had additional allergic diseases. This 18% difference was not found to be statistically significant (p=0.210). Food allergen positivity was detected in approximately one-quarter of cases; no statistically significant relationship was found between the presence of a food history and food allergen positivity (p=0.570). The sensitivity of the patient´s dietary history in detecting food allergen positivity determined by laboratory tests is low (≈33%), specificity is moderate to high (≈75%), and overall agreement is very poor (Cohen´s κ ≈ 0.07). nsLTP positivity was 1%, and it was observed in conjunction with concurrent multiple food component positivity; omega-5 gliadin (Tri a 19) positivity was detected in 2% of patients and showed clinical correlation. The greedy set-cover approach applied to positive cases showed that a minimal panel consisting of 16 components covered 56 of the 58 positive patients (95% of the target patients).

Although the broad panel CRD at CU reveals the sensitization profile in detail, the high negative rate and, in particular, the limited clinical history–test concordance mean that expanding the panels in routine practice may provide very limited additional benefit. Considering that findings are concentrated in specific components, a targeted panel approach focused on high-yield components and guided by clinical history may be a more rational and cost-effective option, without excluding rare but clinically critical components.