An analysis of 145 oral almond challenge tests

A) Background: Tree nuts are known to be capable of causing severe allergic reactions. However, little has been reported about the details of oral challenge tests of individual tree nuts. The purpose of the study was to analyze the risk factors of a positive almond challenge test performed at Sagamihara National Hospital.

B) Method: Subjects were 145 patients who had received an open almond challenge test of greater than 3g from March, 2006 to April, 2014 at Sagamihara National Hospital. The oral food challenge (OFC) was administered in either 2 divided doses in a 1 hour interval or 3 divided doses in 30 minute intervals. After each challenge, the patient was observed for at least 3 hours. At any sign of subjective or objective symptoms deemed clinically significant, the challenge was terminated and necessary treatment was provided. We had measured patients’ almond specific IgE within one year of the challenge. Patient characteristics, positive rate of OFCs, and symptoms induced by OFCs were retrospectively analyzed.

C) Results: The age range of the 145 subjects was from 1.0 to 16.0 years (median, 7.0 years). There were 103 male (71%) and 42 female (29%) patients. Median almond specific IgE ranged from less than 0.35 to 68.1 kU_A/L (median, 2.84 kU_A/L). Almond had been eliminated from the children’s diet due to an immediate reaction to almond in 10 (6.9%) patients, due to a positive almond specific IgE in 117 (80.7%) patients, and for other reasons such as anxiety of parents in 18 (12.4%) patients. None of the 10 patients with a history of an immediate reaction to almond had experienced a case of anaphylaxis. Associated atopic disorders were atopic dermatitis in 72 (50%) patients, asthma in 35 (24%) patients, allergic rhinitis in 52 (36%) patients, and allergic conjunctivitis in 35 (24%) patients. OFC was positive in 7 (4.7%) of 145 patients. Symptoms in positive OFCs were oral mucosal symptoms in 5 patients, cutaneous symptoms in 3 patients, and gastrointestinal symptoms in 2 patients. There was no case of anaphylaxis. In the 4 patients who required treatment, only a dose of oral antihistamine was needed. In the comparison of OFC positive and negative patients, a significant difference was seen in history of an immediate reaction to almond (43% vs 5%, p=0.007). No significant difference was seen in other factors including almond specific IgE (1.38 kU_A/L vs 2.84 kU_A/L, p=0.33).

D) Conclusions: The only risk factor of a positive almond challenge was a history of an immediate reaction to almond. OFCs should be performed in patients sensitized to almond to confirm the diagnosis, especially in those patients without a history of an immediate reaction to almond.