Component testing - would you abandon your Epi-Pen?

[booandbrimom]

I've been doing a lot of reading lately on component testing. I ran across this presentation from Phadia:

http://www.networks.nhs.uk/nhs-networks/paediatric-allergy-network-of-east-anglia-panea/documents/educational-material/Allergen%20Components%20Presentation.pdf

There is some amazing information in here about egg allergy and about hazelnut/birch cross-reactivity. One line, though, really caught my attention: "Epipen likely not needed" (in response to a child's test results that showed cross-reactivity to birch instead of peanut allergy).

Would you feel comfortable at this point giving up your Epi-Pen if a test like this showed your child was not allergic to one of the nasty proteins? Would you insist on a challenge? Or would you just ignore the testing and go on life as usual?

One other interesting stat - only 22.4% of people diagnosed with a peanut allergy solely from testing actually have one, according to this presentation.

[CMdeux]

Boy.... that is the sixty-four-thousand-dollar question, isn't it?? _{(and just as an aside... 64K sure doesn't seem like as much $ as it used to...)}

I think that I'd need a challenge before I'd be comfortable not carrying epi for an allergen that has a high rate of producing anaphylaxis (obviously undifferentiated component testing, that)... and certainly I'd be nervous about it in someone who had ever had a convincing systemic reaction of ANY kind...


the other thing that I seriously wonder is if component testing-- thus far-- hasn't ultimately elicited a highly BIASED sample, which is skewing their numbers significantly toward "this component isn't associated with anaphylaxis."  Here's what I mean by that...


A randomly selected group of PA patients tested with component testing (and we're talking MANY thousands of people with all kinds of rxn hx) could concievably elicit REALLY wildly different distribution from what they HAVE actually seen from people who opt for component testing.

Who opts for it??

a) people without reaction history at all

b) people who have mild reaction history

So yeah, among THOSE people, maybe Ara h8 or Ara h9 isn't an anaphylaxis trigger...

But who's to say that it isn't a trigger for those who have the ability to anaphylax, eh?

THAT is my fear re: component testing, ultimately.  I'm suspicious that it may not mean what clinicians wish that it meant.  This is not a correlation that can (legitimately) be treated as though it's CONVERSE were also true.

As for the 22% figure, that's about what Hugh Sampson once extemporized, too.  There are a LOT of people out there with positive tests that have no clinical allergy.

[hedgehog]

I don't think I'd be comfortable at all.  DS has completed his desensitization.  He eats 3 peanuts every day.  BUt he still does not go anywhere without his epi.  I would not be comfortable with him giving it up, and I don't think he would be either. So just on the basis of testing that says his allergy is not likely to need an epi-pen?  Nope.  Maybe over time, when more is known of how accurate it is, but not as it stands now.

[GoingNuts]

When Dr. Nowak from Mt. Sinai dangled this possibility in front of us, I started thinking about this immediately.  One of the reasons I didn't push DS more to do the testing, is that I didn't want him to feel that he could stop carrying his epi.  My reasoning:

1)  This testing is new, and I'd certainly want to see more data on whether those who were "cleared" ended up needing their epipens subsequently;
2)  Based on his past reactions, even if his allergy is more birch related than nut protein related, there might still exist the possibility of a reaction severe enough to require an epipen.  (Elder son was advised to carry epi even after his presumed hazelnut and soy allergies were proven to be birch related, due to the severity of his OAS reactions.)

And yes, what CM said about the possibility that component testing really doesn't give us the information we hope it does.  And I'd certainly insist on a challenge before making any changes.

DS agreed to revisit the issue in a year, so we have time to think about it and review results.

[twinturbo]

Epinephrine likely not needed. That's not terribly reassuring nor does it say anything of threshold that would dictate level of avoidance needed. I would think if epinephrine is on hand it's because it's already hit the fan. Am I getting the component testing done for the kids? Yeah... as another, if novel, data point. Does it change our lifestyle? I don't see how.

By the way we were talking to the uKnow people today to negotiate a better lab for the draw. We also locked in at $150 if anyone is interested talk to them first.

[booandbrimom]

I remember throwing around the theoretical question about *proving* an allergy. I think we're getting closer to that day.

I can see a time in the future where schools will accommodate only those who can provide the right test results. Parents who don't want to take the test will be seen as fakers.

There's a societal cost to all those epinephrine prescriptions as well...should insurance have to pick up the tab on something that's not likely to be needed? When does cost trump risk?

Does anyone know if all allergens are available? I've only seen peanut on the uKnow site, yet someone else told me her doctor ordered an egg component test and the presentation references other allergens as well. We've already done the hard path to confirm my son's peanut allergy, but it would be worth it to us to do this testing to prove the hazelnut number is really just birch.

We haven't seen our allergist recently - perhaps uKnow is being marketed directly to parents? Will have to find out which institutions have purchased the ImmunoCAP ISAC.

[booandbrimom]

OK, I got less lazy and went and looked it up. (Ironically, it was my husband's work website that held the answer.)

There are 103 component tests available, but they haven't nailed every allergenic protein within each allergen. Sounds like peanut is well documented, so that's why they're pushing it so hard.

Thought you'd appreciate this one:

http://invitrodiagnostics.medicaldevices-business-review.com/news/phadia_unveils_immunocap_isac_and_immunocap_hr_at_the_2009_annual_meeting_of_the_american_college_of_allergy_asthma_and_immunology_091112

David Esposito, President of Phadia US says: "Food allergies are some of the most difficult to diagnose, and create confusion and sometimes even hysteria with patients."

Nice to know we have fans.

[CMdeux]

"hysteria."


GGA.  What is this, the steampunk version of my life, now??   


Because I'd have SWORN that this term was... er... not-very-politically-correct when used in ANY context by anyone associated, however tangentially, with the medical professions, given its EGREGIOUS past misuse and use as a cover for all sorts of nasty treatment (or lack of ANY treatment, for that matter) in women.

Ick.

[Mfamom]

I want to do this test with my ds.  I went to do it and was told by the office that they had all the paperwork etc. 
got there, of course they did not. 
I want to do it because we have anaphylaxis 10 years ago.  No problems since.  a spt was performed to confirm the anaphylaxis.  (no rast )  We've had 2 rast tests come back negative for peanut.  spt though always has 17mm wheal.  My ds is highly allergic to birch and his spt for that is unreal.
So, I was hoping that the component test might give us more information.  Not sure if it will or not. 
to answer the question, no I would not toss epi pen on a test alone.  I would want a food challenge. 
Right now, no one will do challenge on my ds due to his history.  I am not sure if they would if component testing was also negative.

[Ra3chel]

"hysteria."


GGA.  What is this, the steampunk version of my life, now??   


Because I'd have SWORN that this term was... er... not-very-politically-correct when used in ANY context by anyone associated, however tangentially, with the medical professions, given its EGREGIOUS past misuse and use as a cover for all sorts of nasty treatment (or lack of ANY treatment, for that matter) in women.

Ick.

My womb is wandering just looking at this. Then, again, I hear hysteria can be literacy-induced, which is why up-to-date medical science recommends that ladies avoid any activity more strenuous than embroidery and perhaps the occasional graceful swoon.

ETA: My allergies have thus far been unpredictable, and I have a nasty history of developing both new allergies and new severe rxn triggers without warning. I'm'a keepin' my epi-pens.

[CMdeux]

Good to know.   I was really peeved that this new version of my life came with no awesome hat, goggles or corset (other than the obvious metaphorical one imposed by men using terms like "hysteria" at random to describe "undesirable" behavior).

  The least I should get in my pseudo-Victorian alternate reality is good costuming.  And maybe an multi-purpose steel-boned umbrella so that I can whack on those who insist on using the word "hysteria" in conjunction with the word "patients" when that is probably a surrogate term for "patients and/or their parents, mostly female."   

[GoingNuts]

My womb is wandering just looking at this. Then, again, I hear hysteria can be literacy-induced, which is why up-to-date medical science recommends that ladies avoid any activity more strenuous than embroidery and perhaps the occasional graceful swoon.

Lest we come down with a bad case of the vapors.

Seriously Ra3chel, your post should have had a disclaimer warning me to swallow all tea before reading.  I almost ruined another keyboard. 

[hopechap]

I had my son do the test because I wanted more reassurance that it is okay for me to send him to camp and for long playdates, etc. I don't think I would throw out the Epi.  But just wanted to know that our risk taking was less risky.

Got back that he is, in fact, allergic to peanut protein (with alot of birch pollen thrown in).  I did not get which ar h -perhaps they tried to explain and I had a Dr with an accent and a bad connection.  So I do hope they send me the information.

But son was signed up for camp (peanut free FAS member recommended).  And for playdates.

So, I geuss it did not make a HUGE difference to know this. Just bummed anew that he is allergic to peanuts.  I may have been more tempted to send him to a non-peanut free camp - wilderness camp - next year - but now I may not be so brash/rash   -- might not be so rash! ha ha bad pun.  sign of hysteria, no doubt,

[ajasfolks2]

Disclaimer:  haven't closely read all of the above posts.

So, if you have doc who will order these . . . what other questions might you ask as to what the results "mean" or do NOT "mean" so far as how to manage the LTFA?  And/or how might this CHANGE the allergist's official "diagnosis" of LTFA/anaphylaxis to peanut?

What else to ask board certified allergist as to interpreting the results and ACTING on them?

[booandbrimom]

So, if you have doc who will order these . . . what other questions might you ask as to what the results "mean" or do NOT "mean" so far as how to manage the LTFA?  And/or how might this CHANGE the allergist's official "diagnosis" of LTFA/anaphylaxis to peanut?

What else to ask board certified allergist as to interpreting the results and ACTING on them?

So if I understood everything I read over the last couple of weeks...

It's possible to have high numbers to peanut that are the result of cross-reactivity to pollen. If the Ara h 8 protein is high and the Ara h 2 protein is low (particularly if 1 and 3 are also low), then the interpretation is that your child may have a pollen-only allergy and a challenge test is in order.

Conversely, if you see a high number for Ara h 2, your child most likely has a real peanut allergy. If you also see high numbers for other allergens, it may signal the potential for serious reactions. This is less diagnostically certain because the theory is that it's about the number of "hot spots" on each allergen for which the body has developed antibodies and it's possible to have lots of hot spots for only one allergen...but the number of allergens are a rough proxy for an increase in the number of epitopes/hot spots.

As many as 75% of allergies diagnosed by testing only may be pollen x-ref...so this is very worth doing if your child has never had a reaction to peanut. If the *have* had a reaction, then it's mostly entertainment value.