Comparison between two commercial immunoassays: Dr. Fooke ALLERG-O-LIQ versus Phadia ImmunoCAP® System in detecting allergen-specific IgE and total IgE values*

Abstract Objective Beside patient's history and skin prick testing(SPT) the detection of specific IgE(sIgE) represents an important tool of allergy diagnostics. In recent years different technologies for the detection of sIgE have been developed. The objective of this study is the comparison of the ALLERG-O-LIQ with the ImmunoCAP® System using seven inhalant and four food allergens. Methods Sera from patients were collected and tested for sIgE to inhalant(d1, d2, d5, i6, e1, e5 and m3) and food allergens(f1, f2, f24, f24) by ALLERG-O-LIQ(Dr. Fooke Laboratorien GmbH) and by ImmunoCAP® System(Phadia). Further, samples were also tested for total IgE in both systems. Results Prevalence of positive test results varied between 0/20(f24) and 11/20(e5) for ALLERG-O-LIQ and between 3/18(f23) and 11/20(d1/d5) for ImmunoCAP®. The qualitative agreement between both methods was found between 75%(f24) and 100%(d2) depending on the allergen. Overall qualitative agreement for inhalant( n = 140), food( n = 78) and all allergens( n = 218) tested was 92.1%(kappa = 0.84), 83.3%(kappa = 0.58), 89.0%(kappa = 0.77), respectively. Sensitivity, specificity, positive predictive value (PPV), negative predictive value(NPV) and diagnostic efficiency(DE) were found at 88.2%, 95.8%, 95.2%, 89.6%, 92.1%(inhalant allergens), 62.5%, 92.6%, 78.9%, 84.7%, 83.3%(food allergens) and 81.5%, 94.4%, 91.5%, 87.5%, 89.0%(all allergens). Conclusion Good to excellent qualitative agreement between ALLERG-O-LIQ and ImmunoCAP® for the detection of specific and total IgE could be observed. The degree of agreement depended on the allergen and was higher in the group of inhalant allergens. The ALLERG-O-LIQ System represents a reliable test for the detection of specific and total IgE.