D2.187 - Are Component-Based Skin Tests Reliable? Correlation between Skin Prick Testing and Specific IgE to Der p 1, Der p 2 and Der p 23

Component-resolved diagnostics (CRD) in serum are increasingly used to identify candidate allergens for allergen immunotherapy. However, serological testing increases costs, may delay treatment initiation, and often requires additional clinical visits. The availability of purified component-based extracts for skin prick testing (SPT) could represent a practical alternative to serum-based CRD.

Patients with allergic rhinitis sensitized to Dermatophagoides pteronyssinus were recruited. SPT was performed using purified molecular extracts of Der p 1, Der p 2 and Der p 23. Results were compared with serum specific IgE (sIgE) levels to the corresponding components using correlation analyses and logistic regression models

A total of 54 patients were included; 61.1% were male, with a mean age of 21.9 years (SD 11). Comorbidities included asthma (30%), atopic dermatitis (20%), food allergy (7%) and chronic urticaria (5%). Mean SPT wheal diameters (± SD) were 9.9 ± 3.2 mm for whole D. pteronyssinus, 5.3 ± 3.8 mm for Der p 1, 5.7 ± 3.2 mm for Der p 2 and 6.4 ± 4.4 mm for Der p 23. Median (IQR) serum sIgE levels were 419 kU/L (1085) for whole D. pteronyssinus, 17.2 kU/L (52.3) for Der p 1, 21.8 kU/L (73.3) for Der p 2 and 6.4 kU/L (14.8) for Der p 23. Significant correlations were observed between SPT wheal size and component-specific sIgE for Der p 1 (r = 0.48; p < 0.001) and Der p 2 (r = 0.41; p < 0.05). SPT responses to Der p 1 also correlated with sIgE to the whole D. pteronyssinus extract (r = 0.47; p < 0.01). A positive SPT to Der p 1 and Der p 23 was strongly associated with CRD positivity (OR 266; 95% CI 14.8–4770; p < 0.001 and OR 46.3; 95% CI 4.3–500.7; p < 0.01, respectively), with positive predictive values of 97.4% for both components.

Component-based SPT shows high concordance with serological CRD. Although correlations with component-specific sIgE are moderate and insufficient to reliably estimate serum IgE concentrations, component-based SPT may represent a useful diagnostic strategy when the clinical objective is to identify sensitization status rather than quantify IgE levels.