Retrospective analysis on the agreement between skin prick test and serum food specific IgE antibody results in adults with suspected food allergy

BACKGROUND Food allergy is a common clinical problem in adults. Given logistical barriers to conducting food challenges, the use of skin prick test (SPT) and specific IgE (sIgE) are important in establishing the diagnosis. The purpose of this study is to investigate the agreement of SPT and sIgE results in adults presenting to an allergy clinic with suspected food allergy. METHODS Retrospective analysis of medical records at the University of Alberta Allergy Clinic between September 2013 and May 2015 was performed. Demographic, medical history as well as SPT and specific IgE results were recorded. Agreement of SPT and sIgE for individual food allergens was analyzed by Kappa statistics. RESULTS Data from 260 patients was collected. The population was predominantly female, often having other atopic diseases. Very few food challenges were performed; IgE mediated food allergy was diagnosed in a minority (29.6 %) of cases. Kappa values which reached statistical significance were moderate for peanut ĸ = 0.535 (p = 0.0002, CI 0.364-0.707), walnut ĸ = 0.408 (p = 0.001 CI 0.159-0.657), pecan ĸ = 0.530 (p = 0.001 CI 0.211-0.848), and lobster ĸ = 0.543 (p = 0.004 CI 0.197-0.889), substantial for pistachio ĸ = 0.657 (p = 0.023 CI 0.224-1.000), codfish ĸ = 0.770 (p = 0.0002 CI 0.558-0.983), shrimp ĸ = 0.627 (p = 0.0006 CI 0.383-0.871) and egg white ĸ = 0.625 (p = 0.002 CI 0.293-0.957), almost perfect for cashew ĸ = 0.894 (p = 0.0008 CI 0.693-1.000) and salmon ĸ = 0.874 (p = 0.004 CI 0.705-1.000). CONCLUSIONS The agreement between SPT and sIgE results on adults being evaluated for food allergy is at least moderate or better for peanut, walnut, pecan, pistachio, cashew, lobster, shrimp, codfish, salmon and egg white. This should be reassuring for patients who have contraindications or restricted access to either test as the results for the above allergens will likely agree. These findings may suggest that these tests could possibly be interchangeable in adults being evaluated for suspected food allergy and will aid primary care physicians in the triage of patients requiring allergist care.