The purpose of the study is to analyze the risk factors of a positive oral food challenge (OFC) to cashew nut (CN) performed at Sagamihara National Hospital.
B)Methods
Subjects were 71 patients who had received an OFC of more than 1g of CN for the purpose of diagnosis or confirmation of tolerance acquisition from June, 2006 to August, 2014. We had measured those patients’ CN specific IgE within 1 year of OFC. We retrospectively analyzed OFCs and the patients’ background. When clear objective symptoms were seen, OFC was judged as positive. When symptoms were unclear at OFC, we concluded the final diagnosis by confirming the reproducibility of the symptoms at home until their next visit at outpatient.
C)Results
Of the 71 patients 50 were male, 21 were female. Median age was 7.5 years with a range from 3.3 to 22.5 years. The reason for elimination of CN in 8 patients (including 2 with anaphylaxis) was a history of immediate reaction to CN. Fifty seven patients had eliminated CN due to a positive CN specific IgE. Atopic dermatitis was seen in 76% (54/71), asthma 45% (32/71), allergic rhinitis 36% (27/71), allergic conjunctivitis 17% (13/71). History of immediate reaction to nuts other than CN was seen in 23% (16/71) of the patients and history of immediate reaction to peanut in 31% (22/71). Eighteen % (13/71) of the patients were positive in OFC and 82% (58/71) negative. Of the 13 patients with a positive OFC, anaphylaxis was seen in 5 patients. Oral mucosal symptoms were seen in 9 cases, gastrointestinal symptoms in 9 cases, cutaneous symptoms in 7 cases, respiratory symptoms in 6 cases, neurologic symptoms in 3 cases and cardiovascular symptoms in 1 case. Seven patients were treated with antihistamine, 5 patients with steroids, 4 patients with inhaled β2 stimulant and 1 patient with adrenaline. In the comparison of OFC between positive and negative patients, a significant difference (p<0.01) was seen in a history of immediate reaction to CN and CN specific IgE. There was no significant difference in other factors including sex, age, history of immediate reaction to nuts other than CN, immediate reaction to peanut and anaphylaxis due to CN.
D)Conclusions
A history of immediate reaction to CN and high CN specific IgE were risk factors for a positive OFC. CN OFCs in patients with these risk factors should be performed with caution, considering the possibility of anaphylaxis.