372 Skin Prick Test Reactivity Compared to Serum Specific IGE by ISAC in Patients With Rhinitis

Background Microarray technique is promising in allergy diagnosis. The aim of this study was to compare SPT with specific-IgE by microarray in a group of patients with rhinitis. Methods Cross-sectional study, 101 participants with rhinitis diagnosed according to ARIA (89.1% with asthma); age range 6 to 15 years. SPT was done with Dermatophagoides pteronyssinus (Dp), Blattella germanica (Bg), cat and dog allergenic extracts (IPI ASAC Brasil); a mean wheal diameter of ≥2 mm greater than the negative control was considered positive. Sera were analysed for allergen specific IgE antibodies to Dp (Der p 1, Der p 2), Bg (Bla g 1, Bla g 2, Bla g 4, Bla g 5), cat (Fel d 1, Fel d 2) and dog (Can f 1, Can f 2) allergens using a microarray system (ImmunoCAP ISAC, PMD, Austria), considered positive ≥0.3 ISU (ISAC standardized units). Categorical variables were shown as percentage and differences between the 2 methods verified by chi-square test; P < 0.05 was considered significant. Results SPT was positive to Dp in 88.1% whereas ISAC was positive to Der p 1 in 74.2% (P < 0.001) and Der p 2 in 73.3% (P < 0.01) respectively. Sensitivity of SPT was 97% and specificity was 38%. The remaining allergens caused less SPT reactions (cockroach 25.7%, cat 22.8%, dog 27.7%) and these were associated with lower detection of specific-IgE by ISAC respectively Bla g 1 (0.9%, P = 0.09), Bla g 2 (0%), Bla g 4 (0%), Bla g 5 (0.9%, P = 0.55); Fel d 1 (16.8%, P < 0.01), Fel d 2 (0.9%, P = 0.06); Can f 1 (4.9%, P = 0.53), Can f 2 (2.9%, P < 0.001). Conclusions SPT remains the favored method to detect IgE-mediated sensitivity to aeroallergens. SPT was highly sensitive for Dp though less specific in comparison with the IgE microarray to Der p 1 and Der p 2 allergens.