Ana o 3 sIgE and diagnostic algorithms reduce cost of cashew allergy
diagnosis in children compared to skin prick test: a cost comparison
analysis
Abstract
Background: In the absence of a clear clinical history of
reaction, diagnosis of cashew allergy using skin prick tests (SPT) or
cashew-specific IgE requires a high number of oral food challenges
(OFC). By using Ana o 3 sIgE alone, or a two-step diagnostic algorithm
using cashew sIgE followed by Ana o 3 sIgE, there is a reduced need for
OFC. We aimed to perform a cost comparison for both of these approaches
compared to cashew SPT alone. Methods: Pooled individual level
data from 6 studies was used to determine diagnostic accuracy and OFC
rate. Two studies used cashew SPT (n=567, 198 allergic), with 95%
positive and negative predictive values of ≥12mm and <3mm.
Four studies were included in the pathways for Ana o 3 sIgE alone or a
2-step algorithm incorporating cashew and Ana o 3 sIgE (n=271, 156
allergic). Cut-offs used were ≥8.5kUA/L and ≤0.1kUA/L for cashew sIgE
and ≥0.35kUA/L and ≤0.1kUA/L for Ana o 3 sIgE. Costs were constructed
based on unit prices from hospital inpatient admissions, expenses
incurred by families, individual patient data on allergic reaction types
and rates and adrenaline autoinjector carriage, applying a health system
perspective. Results: Modelled data through the Ana o 3 pathway
resulted in a 46.43% cost reduction (\euro307,406/1000 patients)
compared to using cashew SPT alone (\euro573,854/1000 patients). The
2-step algorithm resulted in a 44.94% cost reduction compared to SPT
alone (\euro315,952.82/1000 patients). Both the Ana o 3 pathway and
2-step algorithm resulted in a 79-80% reduction in OFCs compared to
SPT. Conclusions: Using Ana o 3 as a standalone test for cashew
allergy diagnosis or a 2-step algorithm incorporating cashew sIgE and
Ana o 3 sIgE is accurate and results in a large reduction in both OFCs
and health system costs compared to cashew SPT alone.