Immediate Type Reaction of Food Allergy Confirmed by Open Food Challenge Test: Diagnostic Value of History and Skin Test in Food Allergy

Lee, Ki Young; Kim, Kyu Earn; Jeong, Byung Ju

Abstract

PURPOSE
Food allergy is one of the common allergic diseases and elicits various clinical manifestations in children. Although the offending food could be suspected by history of food allergy and skin test with food allergen, it should be confirmed by food challenge test. We investigated the result of open food challenge test(OFCT) with offending food as suspected by history and/or skin test. Thereafter we analyzed the relationship between positive history of food allergy and positive skin test to food allergen, and positive food challenge test.
METHODS
The subjects consisted of 208 children (age range, 3-15 years) with history of food allergy and/or positive skin test to food allergen. Open food challenge test was performed in 276 cases with 33 kinds of suspected foods. Increasing doses of natural food were given every 20 minutes, and the clinical manifestations elicited by challenge test were observed for 1 hour.
RESULTS
1) One-hundred twenty eight of 276 cases were positive for OFCT, and the provocation rate was 46.4%. 2) The provocation rate of individual food was highest in buckwheat flour(72.3%), followed by crab(60.0%), shrimp(45.8%), milk(41.6%), and egg(41.4%). 3) OFCT elicited allergic manifestations in 44.8% of positive history alone and 31.1% of positive skin test alone. Allergic manifestations were elicited in 91.2% when both the positive history and skin test were positive for the same food. 4) Positive and negative predictive values for OFCT were 67.8% and 68.9% in history, 46.8% and 55.2% in skin test, and 91.2% and 65.3% in history and skin test respectively. 5) Urticaria was the most common symptom(84.4%) elicited by OFCT. There were various allergic manifestations such as asthma, rhinitis, conjunctivitis and burning sensation in throat. Anaphylactic shock was observed in 3 cases with buckwheat flour allergy. 6) For the most cases(51.5%) symptoms occurred by the ingestion of small amount(1-100gm) of offending food. But symptoms in 27 cases were elicited just by scrubbing the food on lips or licking it by tongue.
CONCLUSIONS
Open food challenge test showed the highest positive provocation rate with buckwheat. The most common symptom was urticaria, which was elicited with only a small amount of offending food. In predicting the result of OFCT, food allergy history was more reliable than the positive skin test, and if both the history and the skin test were positive for the same food, almost all the cases showed positive results with OFCT.