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.