Related:

http://www.medscape.com/viewarticle/753505

From Medscape Medical News

Food Allergy in Kids Not Being Optimally Diagnosed

Author: Fran Lowry


From Medscape Allergy & Immunology
Medscape Medical News from the:
American College of Allergy, Asthma & Immunology (ACAAI) 2011 Annual Scientific Meeting
November 3 - 8, 2011; Boston, Massachusetts

Bumping

Posted: 08/24/11 at 06:21 pm
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Peanut allergy: Overestimated in epidemiology or underdiagnosed in primary care?

  (It's from The Journal of Allergy and Clinical Immunology, Volume 127, Issue 3 , Pages 631-632, March 2011.)

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There is no abstract for that one, which is a sort of mini-review article.  The upshot, apparently, is that MANY--okay, the vast majority of the kids included in the recent dramatic upward swing in diagnoses-- are NOT clinically allergic.  The alternative is that if all of the phone and physician surveys are correct, there may be significant UNDER-estimation instead, which is worrying in itself because so few of those people are carrying emergency meds.  Make sense?


This is merely a discussion of the problem-- this is the research article itself:

http://download.journals.elsevierhealth.com/pdfs/journals/0091-6749/PIIS0091674909015346.pdf?mis=.pdf&refissn=0091-6749&refuid=S0091-6749%2811%2900115-1

The article estimates that as many as 80% of them are false diagnoses, when you take out those with convincing history-- and then food challenge those who have low RAST levels.

Even if one were to assume that they might have a population error of as much as 20% (which would be pretty large, given the methodology in the paper, I think)-- that still means that way more than half of the people who TEST positive for a peanut allergy are not clinically allergic. 

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Posted: 08/24/11 at 06:27 pm
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And why was I so interested in this article, you ask?

Well-- because of this.

Phadia Announces First-Ever Commercial Availability of Peanut Allergen Component Tests

It's been a lot more than "five years"    since a researcher (at McGill Uni, I believe) suggested initially that profiling PA populations and evaluating individual protein sensitization might be a tool to differentiate who is truly at risk among those sensitized to peanut proteins via IgE. 

It looks an awful lot like that day may be inching closer! 

This would be terrific news, because it would mean a way to let that 60% (80%? whatever it turns out to be) know that a food challenge is a SAFE thing to try even though they "tested" positive for a peanut allergy.

Too many people are blindsided by a diagnosis, and in the absense of history and presence of a high RAST, have no way out.  I really am excited that this might help some people!   Because this is no way to grow up-- unless you really DO have to.

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Posted: 09/01/11 at 04:40 am       

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DD had this testing done in Wisconsin about a year and a half ago. Unfortunately, DD was high on Ara h 2 and one other protein they didn't want to see (can't remember which number right now). Interestingly, the Phadia testing showed no allergy to cashews, which have always been quite high with ImmunoCap. We're obviously still avoiding, especially given that she is allergic to about every other tree nut lurking out there. Boo. 

One other thing that bothered me about the validity of Phadia is that she tested negative for almost all environmentals, which I KNOW is not true. (Four years of allergy shots and she still is pretty miserable from Spring to Fall). So, I dunno. It will be intersting to see how the component testing plays out with larger populations... 

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Posted: 09/01/11 at 06:55 am       

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That's a really good point.

As this rolls out more generally, I hope that it tends to stay a tool for allergists to tease apart who is (or is not) a good candidate for an IOFC.

Not who should "go home and eat Jif, you're not really allergic."   

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09/01/11 at 04:40 am, SaraM wrote:

QuoteDD had this testing done in Wisconsin about a year and a half ago. Unfortunately, DD was high on Ara h 2 and one other protein they didn't want to see (can't remember which number right now). Interestingly, the Phadia testing showed no allergy to cashews, which have always been quite high with ImmunoCap. We're obviously still avoiding, especially given that she is allergic to about every other tree nut lurking out there. Boo. 

One other thing that bothered me about the validity of Phadia is that she tested negative for almost all environmentals, which I KNOW is not true. (Four years of allergy shots and she still is pretty miserable from Spring to Fall). So, I dunno. It will be intersting to see how the component testing plays out with larger populations...

Sara,
My DD tests clinically negative for environmentals (very low RAST well below PPV) but she clearly has environmental allergies. Her RAST is done at Hopkins, which uses Immunocap (IIRC). Dr. Wood and his nurse practioner said it's not uncommon to test negative on RAST to environmentals and have environmental allergies.

I'll be interested in the Phadia testing and will have to add it to the list of questions for Dr. Wood. DD has never had a peanut or peanut butter. Her only known exposure to peanut was Ritz Bits sandwich crackers and she didn't react to those. She was diagnosed first by SPT and the wheal was huge (larger than a saucer) and then a 100+ RAST. She's had one anaphylactic reaction but we don't know exactly what caused it; the suspected item is something likely to either be cross-contaminated with peanut or contain peanut flour. We've been told (again this summer by Dr. Wood) that her peanut allergy will be life-long.