Data collection and Interventions
Patients’ charts were reviewed for demographic, clinical and analytical
data collection. Detailed information for the characterization of the
index reaction (first nut reaction which motivated referral to Food
Allergy Consultation) was obtained. Post-index nut reactions or nut
allergies diagnosed during patients’ allergological investigation were
also assessed. Patients were considered allergic to a specific nut if
they had a suggestive clinical history and at least one positive test of
the following: (1) skin prick/prick-prick tests (SPT/SPPT); (2) sIgE;
(3) OFC. In the absence of previous contact or in cases of previous
ingestion without reaction, and evidence of sensitization to a specific
nut (positive SPT/SPPT and/or sIgE), only those with a positive OFC were
considered allergic. Previous personal and family history of atopy was
also recorded.
Allergological investigation included ST, serum analysis of total IgE,
sIgE for TN and peanut and mcIgE, and OFC. For ST, mean papule diameter
(MPD) ≥3mm above the negative control was considered a positive result.
When SPT was negative or commercial extract was unavailable, SPPT was
carried out. Regarding serum analysis, cut-off value for positive result
for total IgE and sIgE (ImmunoCAP®, Thermo Fisher Scientific) was
>0.35 kU/L, while for mcIgE (ImmunoCAP® ISAC-112, Thermo
Fisher Scientific) was ≥0.1 ISU-E. OFC was performed only in selected
cases, as it is the gold standard for allergy confirmation or exclusion.