Skin prick testing predicts peanut challenge outcome in previously allergic or sensitized children with low serum peanut‐specific IgE antibody concentration

Abstract

Peanut allergy is transient in some children but it is not clear whether quantitating peanut-specific IgE by Skin Prick Test (SPT) adds additional information to fluorescent-enzyme immunoassay (FEIA) in discriminating between allergic and tolerant children. To investigate whether SPT with a commercial extract or fresh foods adds additional predictive information for peanut challenge in children with a low FEIA (<10 k UA/L) who were previously sensitized, or allergic to peanuts. Children from a hospital-based allergy service who were previously sensitized or allergic to peanuts were invited to undergo a peanut challenge unless they had a serum peanut-specific IgE>10 k UA/L, a previous severe reaction, or a recent reaction to peanuts (within two years). SPT with a commercial extract, raw and roasted saline soaked peanuts was performed immediately prior to open challenge in hospital with increasing quantity of peanuts until total of 26.7 g of peanut was consumed. A positive challenge consisted of an objective IgE mediated reaction occurring during the observation period. 54 children (median age of 6.3 years) were admitted for a challenge. Nineteen challenges were positive, 27 negative, five were indeterminate and three did not proceed after SPT. Commercial and fresh food extracts provided similar diagnostic information. A wheal diameter of >or=7 mm of the commercial extract predicted an allergic outcome with specificity 97%, positive predictive value 93% and sensitivity 83%. There was a tendency for an increase in SPT wheal since initial diagnosis in children who remained allergic to peanuts while it decreased in those with a negative challenge. The outcome of a peanut challenge in peanut sensitized or previously allergic children with a low FEIA can be predicted by SPT. In this cohort, not challenging children with a SPT wheal of >or=7 mm would have avoided 15 of 18 positive challenges and denied a challenge to one out of 27 tolerant children.

Reintroduction of Cow’s Milk in Milk-Allergic Children: Safety and Risk Factors

“…Nevertheless, negative (<3 mm) SPT were highly sensitive for a negative challenge outcome, and rather large ones (>7.5 mm) were quite specific. These values were similar to the ones suggested for milk allergy diagnosis (8 mm) [11], as well as for peanut allergy (7.5 mm) [23]. …”

Food allergy: A practice parameter update—2014

“…223 Other investigations have established SPT mean wheal size cutoffs and PPVs for a limited number of common food allergens (Table E3). 219,[224][225][226] These cutoffs can be used to help the clinician establish the probability of clinical reactivity versus oral tolerance and determine the need for further testing (eg, OFC) or dietary manipulations. The clinician should be aware that PPVs of wheal sizes can vary with age 224 or other factors, such as skin test location (eg, volar surface of forearm vs back), SPT device, or reagents (which are not standardized) used for testing.…”

“…Predictive value of IgE testing in positive or negative OFC results[219][220][221][222][224][225][226]228 …”

Peanut allergy: Emerging concepts and approaches for an apparent epidemic

“…Studies are continually emerging that correlate clinical reactions/ food challenge outcomes to test results, and examples are shown in this article's Table E1 in the Online Repository at www.jacionline.org. [58][59][60][61][62][63][64][65][66][67] Most of the studies focused on children, and it must be appreciated that skin test sizes may be affected by variables such as technique, probe type, extract, modality of measuring/reporting, age, and so forth. Discrepancies among studies can also be attributed to variables such as the procedures that define a positive food challenge, inclusion/exclusion from food challenges, and subtleties of regional differences in practice.…”