Integrating Ara h 2 sIgE with SPT reduces oral food challenges and costs in peanut allergy diagnosis: A cost comparison analysis.

Abstract

Background: Peanut allergy consumes a significant volume of oral food challenges (OFC) in the diagnosis of food allergy. Two-step diagnostic algorithms involving both SPT and Ara h 2 sIgE demonstrate increased accuracy of diagnosis in modelled studies compared to peanut skin prick test (SPT) or sIgE to whole peanut, which should result in fewer OFCs. In 2015, The Royal Children's Hospital, Australia (RCH) implemented a clinical guideline using a two-step algorithm incorporating peanut SPT (3-8 mm) followed by sIgE to Ara h 2 if the clinician is considering a peanut OFC. We aimed to determine the OFC reduction in clinical practice as a result of this two-step diagnostic algorithm compared to using peanut SPT alone and perform a cost comparison between these two approaches.

Methods: We performed an audit of all patients presenting to RCH allergy clinics undertaking assessment of peanut allergy. Adherence to the guideline, the number of OFCs required for diagnosis, and outcomes were determined. Modelled data of the same patient cohort estimated the number of OFCs that would have occurred if using peanut SPT alone. A cost comparison was performed, comparing these two approaches.

Results: Eight thousand, eight hundred and twenty-six patients were included, with 9.2% proceeding to an OFC. Of these, 20.1% had a positive result (any allergic reaction), and anaphylaxis occurred in 1.1%. There was a reduction of 27.8% in OFCs when using the diagnostic algorithm compared to SPT alone. Using the diagnostic algorithm also resulted in a 32.05% cost reduction compared to the SPT-only pathway. Sensitivity analysis demonstrated the number of OFCs gives the greatest impact to the overall cost of diagnosis.

Conclusions: A combined algorithm incorporating peanut SPT followed by sIgE to Ara h 2 resulted in a reduction in patients requiring OFCs and a cost saving in a clinical cohort.