Q:

3/20/2014
Are there any studies showing that skin test results are predictive for successful oral challenges to baked egg and/or baked milk? Many of us use sIgE to select patients for oral food challenges to baked egg and baked milk, but I have not read or heard anything about the usefulness of prick skin testing specifically for baked food challenges.

A:

Thank you for your inquiry.

Yes, there are good articles dealing with both issues. I have copied below three examples.

Thank you again for your inquiry and we hope this response is helpful to you.

Allergy Asthma Proc. 2012 May-Jun;33(3):275-81. doi: 10.2500/aap.2012.33.3544.
Role of specific IgE and skin-prick testing in predicting food challenge results to baked egg.
Cortot CF1, Sheehan WJ, Permaul P, Friedlander JL, Baxi SN, Gaffin JM, Dioun AF, Hoffman EB, Schneider LC, Phipatanakul W.
Author information
1Division of Allergy and Immunology, Department of Medicine, Children's Hospital, Boston, Massachusetts, USA.
Abstract
Previous studies suggest that children with egg allergy may be able to tolerate baked egg. Reliable predictors of a successful baked egg challenge are not well established. We examined egg white-specific IgE levels, skin-prick test (SPT) results, and age as predictors of baked egg oral food challenge (OFC) outcomes. We conducted a retrospective chart review of children, aged 2-18 years, receiving an egg white-specific IgE level, SPT, and OFC to baked egg from 2008 to 2010. Fifty-two oral baked egg challenges were conducted. Of the 52 challenges, 83% (n = 43) passed and 17% (n = 9) failed, including 2 having anaphylaxis. Median SPT wheal size was 12 mm (range, 0-35 mm) for passed challenges and 17 mm (range, 10-30 mm) for failed challenges (p = 0.091). The negative predictive value for passing the OFC was 100% (9 of 9) if SPT wheal size was <10 mm. Median egg white-specific IgE was 2.02 kU/L (range, < 0.35-13.00 kU/L) for passed challenges and 1.52 kU/L (range, 0.51-6.10 kU/L) for failed challenges (p = 0.660). Receiver operating characteristic (ROC) curve analysis for SPT revealed an area under the curve (AUC) of 0.64. ROC curve analysis for egg white-specific IgE revealed an AUC of 0.63. There was no significant difference in age between patients who failed and those who passed (median = 8.8 years versus 7.0 years; p = 0.721). Based on our sample, SPT, egg white-specific IgE and age are not good predictors of passing a baked egg challenge. However, there was a trend for more predictability with SPT wheal size.

Clin Exp Allergy. 2013 Oct;43(10):1189-95. doi: 10.1111/cea.12153.
Baked egg food challenges - clinical utility of skin test to baked egg and ovomucoid in children with egg allergy.
Tan JW1, Campbell DE, Turner PJ, Kakakios A, Wong M, Mehr S, Joshi P.
Author information
1Children's Hospital at Westmead, Sydney, Australia; University of Sydney, Sydney, Australia.
Abstract
Background: Many children with IgE-mediated egg allergy can tolerate products containing extensively heated (baked) egg. Aside from food challenge, there are no tests which reliably predict tolerance to baked egg in egg-allergic individuals.
Objectives: To determine if skin prick test (SPT) to baked egg (muffin) and ovomucoid can predict the outcome of baked egg challenges in egg allergic patients.
Methods: In this prospective study, children with a recent history of immediate allergic reactions to egg [and corroborative positive SPT or serum-specific IgE (ssIgE) to egg] or those with SPT/ssIgE > 95% PPV for egg allergy were invited to undergo an open standardized baked egg (muffin) challenge. SPT to egg white, ovomucoid, and fresh muffin were performed immediately prior to challenge.
Results: One hundred and forty-three egg allergic children underwent baked egg challenge and of these, 90 (63%) tolerated 1 g of egg protein in a baked muffin. Of the 53 positive challenges, eight (15%) had respiratory and/or cardiovascular symptoms. The median SPT diameters in positive challenges compared with negative challenges were baked muffin - 6.0 mm/4.0 mm and ovomucoid 7.5 mm/5.0 mm respectively. Receiver operating characteristic (ROC) curves were generated for SPT to baked egg and ovomucoid. The area under the curve was 0.68 for baked egg, and 0.67 for ovomucoid. A muffin SPT of < 2 mm had a negative predictive value of 88% and an ovomucoid SPT ≥ 11 mm had a positive predictive value of 100%.
Conclusions and Clinical Relevance: A SPT of < 2 mm to muffin had a high negative predictive value to baked egg challenge. Ovomucoid SPT ≥ 11 mm was very likely to predict a reaction to baked egg. In these children, deferring the challenge would be appropriate.

Ann Allergy Asthma Immunol. 2012 Nov;109(5):309-313.e1. doi: 10.1016/j.anai.2012.07.026. Epub 2012 Aug 21.
Predicting food challenge outcomes for baked milk: role of specific IgE and skin prick testing.
Bartnikas LM1, Sheehan WJ, Hoffman EB, Permaul P, Dioun AF, Friedlander J, Baxi SN, Schneider LC, Phipatanakul W.
Author information
1Boston Children's Hospital, Boston, Massachusetts 02115, USA.
Abstract
Background: Cow's milk allergy is the most common food allergy in childhood. Many children with IgE-mediated cow's milk allergy may tolerate baked milk products, but few data exist on predictors of outcomes of baked milk challenges.
Objective: To determine the relation of milk protein allergen specific IgE (sIgE) levels and skin prick test (SPT) wheal size with baked milk challenge outcomes.
Methods: A retrospective medical record review was conducted of 35 baked milk challenges. SPT results, sIgE levels, demographic characteristics, and food challenge results were analyzed.
Results: Thirty-five children underwent open challenges to baked milk and 29 (83%) passed. Of those who failed, 3 (50%) passed the initial clinic challenge but developed symptoms to ongoing exposure at home, days to months later. One child who ultimately failed at home required epinephrine. Compared with those who passed, children who failed were younger (median age, 8.9 and 3.7 years, respectively; P = .02). Children with a milk SPT wheal less than 12 mm were more than 90% likely to pass a baked milk challenge, and no child with a milk SPT wheal less than 7 mm failed a baked milk challenge. We were also able to establish more than 90% predictive values for passing baked milk challenges with a casein SPT wheal of 9 mm, a milk sIgE level of 1.0 kU/L, and a casein sIgE level of 0.9 kU/L.
Conclusions: Most children allergic to cow's milk tolerated baked milk. Milk protein SPT wheal may be more reliable than sIgE level in predicting outcomes of baked milk challenges. It is important to be aware of the possibility of late reactions to ongoing baked milk exposure.

Sincerely,
Phil Lieberman, M.D.

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