Double-blind food challenges in children in general paediatric practice: useful and safe, but not without pitfalls

To describe results of double-blind placebo-controlled food challenges (DBPCFC) with cow's milk, hen's egg, soy, peanut and hazelnut in general paediatric practice.

Food challenges were performed between January 2006 and June 2011, in children 0-18 years of age, on two half-day hospital admissions with a one-week interval. Tests were performed in a double-blind fashion following a standardised protocol with validated recipes.

Overall, 234 food challenges were performed in 209 children: 160 with cow's milk, 35 with peanut, 21 with hen's egg, 11 with hazelnuts, and 7 with soy. In two thirds of the cases, the DBPCFC was negative (cow's milk: 57.5%; peanut: 40.0%; hen's egg: 66.7%, hazelnut: 90.9%, soy: 100%). The only patient characteristic significantly associated with a positive DBPCFC was the presence of symptoms from three different organ systems (p=0.007). Serious systemic allergic reactions with wheeze or anaphylaxis occurred in only two children (0.9%). Symptoms were recorded on 29.3% of placebo days. In 30/137 children with a negative test (22%), symptoms returned when reintroducing the allergen into the diet, mostly (66.7%) transient. Of the 85 tests regarded as positive by the attending physician, 19 (22.4%) did not meet predefined criteria for a positive test. This was particularly common with non-specific symptoms.

A DBPCFC can be safely performed in a general hospital for a range of food allergens. The test result is negative in most cases except for peanut. Non-specific symptoms may hamper the interpretation of the DBPCFC, increasing the risk of a false-positive result.