Allergies: A Leickly Story » Food Allergy Support Group

Peanut Allergy Misdiagnosed in 2 out of 3 Cases ?

fleickly — Sun, 25 Apr 2010 18:10:44 +0000

Attacking Peanut Allergy

Peanut Allergy Misdiagnosed in 2 out of 3 Cases

This title from Medical News Today April 13, 2010 caught my attention. It has always been a mystery as to why peanut allergy has increased dramatically over the years. This publication may shed some light on that mystery.

There are a number of factors in the peanut allergy equation and a recalculation may be necessary. First we need to be careful in discerning peanut allergy from peanut sensitization. Peanut allergic children would be those who have symptoms with exposure and evidence of a positive allergy test (skin prick test or specific IgE to peanut determined by a blood test). The sensitizated child is one with a positive test and no clinical correlate.

Secondly, the use of allergy tests has become more frequent and is being done by many other specialties. The manufacturers of blood tests for allergy market to primary caretakers an array of food allergen diagnostic panels that contain peanut along with many other foods. If the history was hives occurring after eating egg, a panel would include egg but would also have a number of additional foods. Sometimes these add-on foods return as positives (despite no history of a problem with ingestion) and the diagnosis of allergy is made.

Thirdly, this news report indicates that the diagnosis of peanut allergy was wrong in 66% of the patients.

A reworking of the prevalence of peanut allergy has a potential confounding variable; faulty diagnostic tools.

This news article began with a poignant comment- peanut allergy has always been associated with a deep anxiety, especially in the parents of peanut allergic children. I have many patients who will attest to that.

“Many people are being told that they are allergic to peanut, that they must avoid them and all foods that contain them at all costs, are actually not allergic to the nut at all” says Professor Wickman (Stockholm, Sweden). Dr. Wickman reported that 2/3 who are considered allergic to peanuts experience mild symptoms or none at all. A cross-reactive protein from birch tree pollen was thought responsible for the peanut reaction.

This report included the shortcomings of the materials used for allergen skin testing and those used for testing the blood for allergy.

To address this issue, a new diagnostic test was used on 4000 children to determine the specific proteins that are cross-reactive. It is known that specific peanut proteins are responsible for allergic reactions to peanut. The new test looks at antibody (IgE) production to the allergy-causing proteins. This allergy component test was used to show that 2/3 children who were diagnosed with peanut allergy were not allergic. Their positive test to peanut was due to some other protein that cross-reacted.

Now this was a news report and not a peer-reviewed article and I know how reporters can get things wrong or misquote. In regards to the report, remember peanut is a legume, not a nut.

In the report a statement is made that…” up to 7.5% of children seemed to be allergic to peanut at age 8 based on routine tests”. This made me wonder if they were truly allergic (symptoms by history) or they were declared allergic because a test was positive (done routinely for allergy?).

Now for a few critical comments- both positive and negative;

1. The capability of sorting out reactivity to the important proteins is applauded. We may be able to go back and de-diagnose a seemingly large proportion of peanut allergic people. The peanut-free tables at the schools are still essential but will be smaller by 2/3.

2. How would this been all different if the diagnostics, both skin prick tests and specific IgE would have been done only in those who had a history of exposure and reactivity with exposure? If the patient’s history directed our choice of individual tests, would we have so many peanut sensitive/allergic people? Avoid doing food allergen panels. Pick out the pertintent allergens- it will be less confusing and it will save money (one example from a local sendout laboratory -$300 for the panel and $25 for the individual allergen).

3. Look at the consequences of marketing panels or doing standard groupings of skin tests or blood tests- in 66% diagnosed perhaps falsely the families have an emotional burden, a nutritional burden, an isolation burden, and a financial burden. The peanut allergic person needs to have self-injected epinephrine available.

4. We always have to be careful in applying the findings from one area to another. This report on the 4000 children was from Sweden. There may be significant differences in our population. I would relish the opportunity to sort out our population of peanut sensitive children.

I am an advisor to the Southside Indianapolis Food Allergy Support Group. In March when I presented an update on food allergy, I promised that I would look at our peanut positive population. This has been quite a task. I am creating a database to characterize the population in the hopes of being able to participate in a peanut study. We have 360 positive skin tests for peanut from January 1, 2009 through March 31, 2010-15 months of clinic visits. The spreadsheet has a number of epidemiologic parameters including the age and type of reaction to peanut. Many of the children were diagnosed based on a panel that was performed because of atopic eczema or due to blood test panels and referred by primary caretakers for further evaluation. A few had anaphylaxis.This project is fascinating and I think will be very informative. It hopefully will catch the eye of those in the allergen diagnostic community or someone looking for a large population to enroll in a peanut immunotherapy study. These families are highly motivated to make a difference and to help others with this problem.

The new technology may help to address a historical and continuing over-enthusiastic and unfocused use of allergy tests, both skin prick test and blood test for peanut allergy. The tests we have now only tell us that antibody (IgE) is being made. The significance of that antibody is left to the clinician and must be based on the history and exposure to the allergen making sure that the clinical condition fits the template of IgE-mediated reactions. I for one eagerly await the arrival of more definitive diagnostic tools.



FEL

Indy Food Allergy Support Groups

fleickly — Thu, 18 Mar 2010 14:38:05 +0000

This past Tuesday (March 16, 2010) I was asked to speak to the Southside Indianapolis Food Allergy Support Group. Last spring I talked about food challenges and what Dr. Vitalpur and I are doing at Riley hospital regarding food challenges. This time I gave an update from the annual meeting of the American Academy of Allergy, Asthma, and Immunology (AAAAI) on food allergy topics. I also shared with the group the request for public commentary on a draft of “Guidelines for the Diagnosis and Management of Food Allergy”. This was a great meeting. I had a very attentive audience who asked many great and probing questions. I reformatted my notes from the conference gave this presentation without any slides to hide behind- now that is a great accomplishment.

We talked about the findings at the meeting. We shared experiences and concerns and we talked about a number of great ideas to help children with food allergy. One of the most thought provoking topics was looking at food allergy as a public health problem. This is definitely a public health problem. As an aside, the request for comments on the ‘ Food Allergy Mangement…’ draft began with a very effective attention getting statement-’Food allergy is an important public health problem….’ . To my dismay (that recent Masters of Public Health degree affecting my perspective again), the guidelines’ intention was to help with diagnosing and managing food allergy and not the public health issues. I applaud this work and the work of the committee that put this together. I have never made any responses to requests for comments on guideline drafts in the past. This draft of the guidelines stimulated me to offer a few comments. The acceptance of these food allergy guidelines is important and desperately needed before we can be effective in any public health approach to food allergy. We need to critically look at what food allergy is and what is not food allergy. We need to listen to the story of what happens with exposures to food and carefully select the appropriate tools/tests to make the diagnosis. We also need to support efforts to help treat current food allergy issues and hopefully prevent the development of food allergy.

I shared with the group a review by Scott Sicherer on ‘What is New in Pediatric Allergy’. In this session Dr. Sicherer selected a few key articles that have appeared over the past year dealing with food allergy. A few of the food allergy topics included; The Natural History of Wheat Allergy (Keet, 2009), Food Protein-Induced Enterocolitis Syndrome (Mehr, 2009), Timing of Food Introduction and the Development of Atopy (Nwaru, 2010), and Dietary Advice, Dietary Adherence, and the Acquisition of Tolerance in Egg-allergic Children (Allen, 2009).

1. Wheat allergy resolved faster than egg or milk allergy.

2. FPIES- depending on the population studied, different foods are causitive and there seems to be differences in the rate of resolution. The overall prognosis is good.

3. Sensitization (having a positive allergy test, not necessarily symptomatic with exposure) was seen with the late introduction of a number of foods in this cohort of children from Finland.

4. Dietary advice is not uniformly followed, the advice given did not correlate with outgrowing egg allergy, adherence to the advice did not correlate with resolution, and accidental exposures to egg did not affect the outcome (outgrowing the allergy).

We also talked about research projects and protocols that involve food desensitization and food tolerance. Wes Burks from Duke University presented information on a number of studies. This work is ongoing at Duke, University of Arkansas, and at Mt.Sinai (New York). It is important to understand the differences between achieving a state of desensitization or tolerance.

1. Desensitization is the temporay increase of the amount of a food that would trigger an allergic reaction. This would offer protection from a life-threatening event due to an exposure.

2. Tolerance is the permanent loss of allergic reactivity due to changes in the immune system.

Desensitization and tolerance may work through similar mechanisms. Small exposures would not cause life threatening events in the desensitized child, however only the tolerant child could eat larger amounts of the culprit food without consequences.

The enthusiasm for participation in studies that may end the fear of a food reaction was intense. I was very impressed. A mother mentioned that she would donate her home if her child could participate in a program that would lead to desensitization/tolerance for peanut.

I shared the findings from an abstract of a study from the University of Michigan (abstract # 746). This was a report from a survey that represented the US population. In this survey 3-4% of those responding had a child with a life-threatening food allergy. Twenty five percent of responders knew someone with a food allergy. Of the families who had a child with a food allergy, 80% were accommodated by the school or daycare and of those, 50% of the staff had specific training in food allergy. Nearly 50% of the responders said that they were not at all inconvenienced by measures needed to protect the food allergic child, 25% were somewhat inconvenienced, and a few said it was very inconvenient for them.

We spent some time talking about this. Some of us were surprised by the findings. The charge to the group and the charge to anyone involved with children with food allergy is to advocate and to make others aware of the issues. The Southside Food Allergy Support Group offers an excellent program called
PAC- Protect Allergic Children. PAC has a detailed presentation that can be given in a number of venues. The programs are ‘Food Allergy Safety in Schools’ and ‘Creating a Safe Home for Food Allergic Families’. Information on these programs can be obtained from the Southside Food Allergy Support Group.

One topic for a future meeting most certainly will be a summary of the final Food Allergy Guidelines.

My thanks to the Southside Food Allergy Support Group for the invitation to speak (as a disclosure, I am an advisor to the group as well). Keep the kids safe!!

Respectfully submitted,

Fred Leickly