The effect of follow-up after a negative double-blinded placebo-controlled cow's milk challenge on successful reintroduction.

Cow's milk allergy is a common food allergy in children with an incidence of 1-3%. The gold standard to diagnose cow's milk allergy is a double-blinded placebo-controlled food challenge (DBPCFC). Previous studies show that reintroduction of cow's milk is unsuccessful in 10-12% of patients. The aim of this retrospective study is to evaluate the effect of follow-up on the reintroduction of cow's milk. We analyzed the data of patients with a negative DBPCFC for cow's milk between 2014 and 2016 in three different departments. Questionnaires were used to compare the three ways of follow-up (no follow-up, follow-up in person or by telephone). Of the 336 children with a negative DBPCFC for cow's milk, 128 questionnaires (41%) were returned. Reintroduction of cow's milk was unsuccessful in 13.3% of the patients. There was no significant difference found between children with (73.8%) or without (26.2%) follow-up, or between follow-up by phone or personally. Whether this finding is caused by small numbers within this retrospective study should be investigated in future prospective studies.Conclusion: Follow-up does not influence the reintroduction success rate of cow's milk after a negative double-blinded placebo-controlled food challenge. What is Known: Diagnosis of cow's milk allergy by double-blinded placebo-controlled food challenge is the gold standard. • After a negative double-blinded placebo-controlled food challenge, reintroduction of cow's milk in the child's diet is unsuccessful in 10-12% of the children. • Recurrence of symptoms, aversion to the examined food, and fear are seen as the main reasons for unsuccessful introduction. What is New: • Reintroduction after a negative double-blinded placebo-controlled food challenge is not influenced by different ways of follow-up.

Predicting reactivity threshold in children with anaphylaxis to peanut.

BACKGROUND: Peanut allergy necessitates dietary restrictions, preferably individualized by determining reactivity threshold through an oral food challenge (OFC). However, risk of systemic reactions often precludes OFC in children with severe peanut allergy. OBJECTIVE: We aimed to determine whether clinical and/or immunological characteristics were associated with reactivity threshold in children with anaphylaxis to peanut and secondarily, to investigate whether these characteristics were associated with severity of the allergic reaction during OFC. METHODS: A double-blinded placebo-controlled food challenge (DBPCFC) with peanut was performed in 96 5- to 15-year-old children with a history of severe allergic reactions to peanut and/or sensitization to peanut (skin prick test [SPT] ≥3 mm or specific immunoglobulin E [s-IgE] ≥0.35 kUA/L). Investigations preceding the DBPCFC included a structured interview, SPT, lung function measurements, serological immunology assessment (IgE, IgG and IgG4 ), basophil activation test (BAT) and conjunctival allergen provocation test (CAPT). International standards were used to define anaphylaxis and grade the allergic reaction during OFC. RESULTS: During DBPCFC, all 96 children (median age 9.3, range 5.1-15.2) reacted with anaphylaxis (moderate objective symptoms from at least two organ systems). Basophil activation (CD63+ basophils ≥15%), peanut SPT and the ratio of peanut s-IgE/total IgE were significantly associated with reactivity threshold and lowest observed adverse events level (LOAEL) (all P < .04). Basophil activation best predicted very low threshold level (<3 mg of peanut protein), with an optimal cut-off of 75.8% giving a 93.5% negative predictive value. None of the characteristics were significantly associated with the severity of allergic reaction. CONCLUSION AND CLINICAL RELEVANCE: In children with anaphylaxis to peanut, basophil activation, peanut SPT and the ratio of peanut s-IgE/total IgE were associated with reactivity threshold and LOAEL, but not with allergy reaction severity.