Correlation of Negative Tree Nut Skin-Prick Tests and Successful Tree Nut Food Challenges Among Peanut-Allergic Children
Sunday, March 6, 2016
South Exhibit Hall H (Convention Center)
Inderpal Randhawa, MD, Christopher P. Parrish, M.D., Tricia Morphew, MSc
Rationale: Children with peanut allergy are regularly instructed to avoid all tree nuts.  However, children with peanut allergy are likely not allergic to all tree nuts.  In our cohort of peanut anaphylaxis patients undergoing oral immunotherapy (OIT), we sought to determine the correlation of tree nut skin prick testing (SPT) results and likelihood of successfully passing a tree nut challenge. 

Methods:  Skin-prick testing was performed to peanut and tree nuts (macadamia, pine nut, coconut, hazelnut, brazil nut, cashew, pecan, walnut, pistachio, almond) in 27 patients with known peanut allergy. The probability of negative SPT (wheal <3mm) for each nut was determined.

Results: All patients demonstrated positive peanut allergy diagnostics in skin test, component testing or food challenge.  Only 15.4% of patients were SPT positive to peanut alone. Macadamia, pine nut, and coconut SPT had a probability of  negative SPT of 0.97, 0.97, and 0.91 respectively. The odds ratio for this group having a negative SPT (compared to a negative SPT) was 46.22. For hazelnut, brazil nut, and cashew the probability of a negative SPT was 0.81, 0.77, and 0.73, respectively. Pecan, walnut and pistachio had odds ratios of 0.68, 0.68, and 0.64, respectively. All patients with macadamia, pine nut and coconut negative SPT subsequently passed 9 gram food challenges without OIT.

Conclusions: Despite current recommendations to avoid all tree nuts for peanut allergic patients, the majority of patients with peanut allergy will have negative skin tests and food challenges to certain tree nuts, especially macadamia, pine nut, and coconut. This pattern was seen despite most patients having multiple nut sensitizations.