Q:

11/14/2013
We are expanding our clinic to include patch testing. We currently skin prick foods when evaluating patients with Atopic Dermatitis. Do you recommend patch testing to foods and inhalants as well, in evaluating this patient? If so, which ones, and would you use the same standardized extract that is used for skin prick testing?

A:

Thank you for your inquiry.

I suggest that if you are considering performing atopic patch testing for foods in your practice that you take a look at a key reference in this regard. It is readily available online. It is entitled “Guidelines for the diagnosis and management of food allergy in the United States: Report of the NIAID-sponsored Expert Panel (lead author is Boyce). It's published in the December 2010 edition of The Journal of Allergy and Clinical Immunology. You can download a PDF and search by using the term “atopy patch test” or simply “patch test,” and this will direct you to the sections in that document that discuss the indications for the use of the atopic patch test and the pros and cons involved in its use. I would pay particular attention to the section “Atopy patch test.” It is found in Section 4.2.2.5. The section is too lengthy to copy and paste here, but I will quote one section directly from this guideline below:

“The Expert Panel suggests that the atopy patch test should not be used in the routine evaluation of noncontact food allergy. Insufficient evidence exists to support the use of the atopy patch test for the evaluation of food allergy.”

This is simply the recommendations of the Expert Panel in brief. I do recommend, however, that you read the entire section so that you may have an understanding of how this conclusion was reached.

To my knowledge there is no indication for patch testing to inhalants.

If you did, however, wish to pursue atopy patch testing further, we have a number of different entries on our “Ask the Expert” website that might be helpful to you. You can access each one of these by going to our website and typing “atopic patch test” into the search box.

In summary, I think, at least to my knowledge, there is no known indication for atopic patch testing to inhalants. At least I am not familiar with an indication in this regard. There are reports in the literature of the usefulness of atopic patch testing to foods in respect to patients with atopic dermatitis and eosinophilic esophagitis. The suggestion of the Expert Panel, however, as noted above, is reserved regarding the use of this test at the present time. Nonetheless, there are data in the literature which indicate that it can be helpful, and some investigators do use the atopy patch test.

Copied for you below is an abstract from one of the most recent articles in this regard from a center which has a great deal of experience in employing the atopy patch test. You will find a rich bibliography in the references which will lead you to a discussion of methods should you wish to pursue the issue further.

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

J Allergy Clin Immunol. 2012 Aug;130(2):461-7.e5. doi: 10.1016/j.jaci.2012.05.021. Epub 2012 Jun 27.
Identification of causative foods in children with eosinophilic esophagitis treated with an elimination diet.
Spergel JM, Brown-Whitehorn TF, Cianferoni A, Shuker M, Wang ML, Verma R, Liacouras CA.
Source
Division of Allergy and Immunology, Children's Hospital of Philadelphia, Philadelphia, PA 19104-4399, USA.
Abstract
Background: Eosinophilic esophagitis (EoE) is a chronic inflammatory disease with isolated eosinophils in the esophagus predominantly triggered by foods. The optimal testing to identify inciting foods remains unclear.
Objectives: We sought to determine the effectiveness of allergy testing-directed diets in patients with EoE.
Methods: A retrospective analysis of all children with EoE seen at the Children's Hospital of Philadelphia between 2000 and 2011 identified 941 patients with EoE. Skin prick tests (SPTs) and atopy patch tests (APTs) were conducted, and predictive values were calculated. IgE-mediated food reactions were also identified. A food was considered to cause EoE if its elimination led to resolution of esophageal eosinophilia or reintroduction led to reoccurrence of EoE. The effectiveness of the various elimination diets was compared with targeted food antigen elimination.
Results: Definitive foods causing EoE were identified, with milk, egg, wheat, and soy as the most common foods in 319 patients. IgE-mediated reactions (urticaria and anaphylaxis) were seen in 15%. The negative predictive value for the combination of SPTs and APTs averaged 92%, with the exception of milk at 44%, and the positive predictive value averaged 44%. An empiric 6-food elimination diet or removal of positive foods on allergy testing (SPTs/APTs) both had a histologic success rate of 53%. Removal of foods identified on SPTs/APTs plus empiric elimination of milk leads to resolution in 77% of patients.
Conclusion: An elimination diet based on SPT/APT results leads to resolution of esophageal eosinophilia in a similar proportion of patients as empiric removal of foods but required that fewer foods be removed. These observations suggest that both methods are acceptable options.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology