Concordance Analysis of ALEX-2, ImmunoCAP, and Prick Test for Respiratory Allergies in Lima, Peru

Background: Accurate identification of respiratory allergen sensitization is essential for managing asthma and allergic rhinitis (AR). While Skin Prick Test (SPT) and ImmunoCAP are standard diagnostic tools, exploratory comparative data for the novel Allergy Explorer 2 (ALEX-2) test in Latin American populations remain scarce. While Skin Prick Test (SPT) and ImmunoCAP are standard diagnostic tools with limited allergen panels per test, the novel Allergy Explorer 2 (ALEX-2) multiplex platform can simultaneously assess multiple allergens. However, exploratory comparative data for ALEX-2 in Latin American populations remain scarce. Methods: This prospective cross-sectional study evaluated the concordance between SPT, ImmunoCAP, and ALEX-2 in detecting respiratory allergen sensitization among 57 patients with asthma or AR recruited consecutively from a private allergy clinic in Lima, Peru. Concordance was assessed using Cohen's κ coefficient. Results: The highest overall agreement was observed between ALEX-2 and SPT (κ = 0.5649, p < 0.0001), followed by ALEX-2 and ImmunoCAP (κ = 0.4911, p < 0.0001), and ImmunoCAP and SPT (κ = 0.4688, p < 0.0001). ALEX-2 and ImmunoCAP aligned on 7 of 10 allergens, while both ImmunoCAP and SPT, as well as ALEX-2 and SPT, agreed on 5 of 9 allergens. The strongest concordance was found for dust mites, particularly Dermatophagoides farinae (κ = 0.6323, p < 0.0001) between ALEX-2 and SPT. Conclusions: ALEX-2 demonstrates moderate agreement with SPT and ImmunoCAP, with the highest concordance for dust mites, suggesting potential as a complementary diagnostic tool pending validation in diverse populations.