Methods: Suspected cashew/pistachio and/or walnut/pecan allergies were examined in 60 patients using specific IgE (n=43 and n=34) measurements, skin prick tests (n=47 and n=34), and double blind placebo controlled food challenges (n=42 and n=30), respectively. Food flours were administered in staged, validated, blinded food challenges using the following dosage amounts: 5 mg, 20 mg, 50 mg, 100 mg, 100 mg, 100 mg, and 125 mg for a cumulative dose of 500 mg. Specific IgE, skin prick test (average wheal size in mm), and eliciting dose for walnut/pecan and cashew/pistachio was analyzed using the Pearson correlation coefficient.
Results: Specific IgE and skin prick tests highly correlated between cashew and pistachio (r=0.93 and r=0.77, p<0.001, respectively) and between walnut and pecan (r=0.78 and r=0.64, p<0.001, respectively). All patients who underwent oral food challenge for cashew and pistachio (n=42) and for walnut and pecan (n=31) were positive for both. However, only moderate correlation was found between the eliciting dose of the food challenge of walnut and pecan (r=0.4, p=0.02) and no correlation was found between cashew and pistachio.
Conclusions: Although high correlation was found in skin prick tests and specific IgE between cashew/ and pistachio and between walnut/ and pecan in multiple food allergic patients, the eliciting dose for one allergen was not correlated with the other.