Predictive value or peanut SPT and sIgE in peanut allergic patients diagnosed of LTP-Syndrome

Patients sensitized to nsLTP comprise a heterogeneous group in terms of sensitization profile, symptom severity and complexity in diagnosis. The aim of this study is to compare sensitivity, specificity, positive and negative values (PPV and NPP) of skin prick test (SPT) and specific IgE (sIgE) in the diagnosis of peanut allergy in patients with LTP-Syndrome. We included 67 patients with confirmed peach allergy. We performed peanut diagnosis based on positive SPT, sIgE and oral food challenge (OFC); except in those that presented ≥ 2 episodes of anaphylaxis in the previous two years. After peanut intake, 30 patients (45%) presented symptoms and 9 (13%) tolerated. Twenty-eight patients (42%) avoid peanut intake because positive SPT and/or sIgE. After OFC, 26 patients (38.8%) were confirmed as allergic to peanut. From 41 (61.2%) who tolerated, 32 (47.7%) had positive SPT and/or sIgE. SPT and sIgE showed a moderate agreement level (kappa=0.50). However, we found a fair level of agreement between SPT and OFC (kappa= 0.20), and sIgE and OFC (Kappa=0.21). These data show the relevance of OFC for confirming the diagnosis of peanut allergy in patients with LTP-Syndrome regardless of the positivity of SPT/sIgE. Further investigations are warranted to clarify the role of LTP in allergy to other plant foods.