Characteristics of tree nut challenges in tree nut allergic and tree nut sensitized individuals.

BACKGROUND: Characteristics and outcomes of tree nut (TN) oral food challenges (OFCs) in patients with TN allergy or sensitization alone are poorly studied. OBJECTIVE: To determine the relation between TN sensitization levels and OFC outcomes. METHODS: Open TN OFCs performed from 2007 through 2015 at a referral center were analyzed to compare outcome based on skin prick test (SPT) wheal size, food-specific immunoglobulin E (sIgE), peanut co-allergy, and TN sensitization only vs TN allergy with sensitization to other TNs. Delayed OFC was defined as longer than 12 months from the time of an sIgE level lower than 2 kUA/L. RESULTS: Overall passage rate was 86% for 156 TN OFCs in 109 patients (54 almond, 28 cashew, 27 walnut, 18 hazelnut, 14 pecan, 13 pistachio, and 2 Brazil nut). Passage rates were 76% (n = 67) in patients with a history of TN allergy who were challenged to another TN to which they were sensitized and 91% (n = 65) in those with TN sensitization only (mean sIgE 1.53 kUA/L; range 0.35-9.14). Passage rates were 89% (n = 110 of 124) for a TN sIgE level lower than 2 kUA/L and 69% (11 of 16) for a TN sIgE level of at least 2 kUA/L. In 44 challenges in patients with peanut allergy and TN co-sensitization, the TN OFC passage rate was 96%. In 41 TN OFCs with a TN SPT wheal size of at least 3 mm, 61% passed, with a mean wheal size of 4.8 mm (range 3-11) in those passing vs 9 mm (range 3-20) in those failing. CONCLUSION: TN challenges are frequently passed in patients with TN sensitization with or without a history of TN reactivity despite a TN SPT wheal of at least 3 mm or a TN sIgE level of at least 2 kUA/L. Nearly all patients with peanut allergy and TN co-sensitization passed the TN challenge, questioning the clinical relevance of "co-allergy."

The economic effect and outcome of delaying oral food challenges.

BACKGROUND: Food specific IgE (sIgE) is a useful marker to assess predictability of oral food challenge (OFC) outcome. A threshold of less than 2 kUA/L for peanut, egg, and milk has been proposed as a 50% negative predictive value at which patients may pass an OFC. OBJECTIVE: To assess the economic effect and outcome of delaying OFCs. METHODS: A retrospective analysis was performed for peanut, egg, and milk OFCs conducted between 2001 and 2012 at a tertiary food allergy referral center. Delayed OFC was defined as greater than 12 months from the time the sIgE level became less than 2 kUA/L. Time to OFC was explored in association with skin prick test result (wheal size), OFC outcome, and the economic effect of delay. RESULTS: Of 319 challenges, 173 OFCs were delayed (54.2%) by a mean time of 35.5 months (range, 13-123 months) vs a mean time of 4.2 months in the 146 challenges that were not delayed (P < .001). The overall OFC passage rate was 89.9%. There was no association between delayed OFC and history of anaphylaxis, type of allergen, age at OFC, or challenge outcome. Delay in OFC was associated with an estimated mean economic cost of $12,203 per patient ($4,184 per 12 months) and $1,951,487 total (total delay, 5,597 months) in this population. CONCLUSION: Despite a 50% negative predictive value, more than 50% of OFCs were delayed in this population by a mean time of nearly 3 years. Delaying OFC is associated with increased costs, and quality improvement is needed to help decrease time to OFC and reduce the economic burden of food allergy on families and the health care system.