Episode transcript
Time stamps
0:45 - Welcome to the first episode of ImmunoCAST.
2:30 - The history of allergies.
5:53 - RAST vs. ImmunoCAP Specific IgE blood testing.
6:48 - Skin tests vs. specific IgE blood tests.
9:31 - Practice parameters and guidelines around specific IgE testing.
13:08 - When would a patient be referred to an allergist vs. being tested in primary care?
15:48 - Lab Ordering Guide for healthcare providers.
18:51 - The future of the ImmunoCAST podcast.
Announcer:
ImmunoCAST is brought to you by ImmunoCAPTM Specific IgE testing and PhadiaTM Laboratory Systems, products of Thermo Fisher Scientific.
Gary Falcetano:
I'm Gary Falcetano
Luke Lemons
And I'm Luke Lemons, with over five years of experience writing for healthcare providers and educating on allergies. You're listening to ImmunoCAST, your source for medically and scientifically backed allergy insights.
Well, yeah. Here we are. The first episode, Gary.
Gary Falcetano:
Yeah. All right. We're going to do this.
Luke Lemons:
I know. How are you feeling?
Gary Falcetano:
Feeling good. We're going to have a nice conversation. It's going to be relaxed, informative. Everybody's going to want to listen.
Luke Lemons:
Yeah. Well, for everyone listening in, welcome to the first episode of ImmunoCAST, your source for medically backed allergy education. I'm Luke Lemons.
Gary Falcetano:
And I'm Gary Falcetano
Luke Lemons:
Yeah. So we're super excited to be sharing this new podcast for healthcare providers, where we're going to be discussing everything and all things allergies.
Gary Falcetano:
For sure. And while this podcast is meant for primary care providers, we encourage specialists and patients to listen in as well, with the hope of providing you with fast, interesting, insightful, and helpful information on all the different facets of allergy. From food and respiratory allergies to guidelines and practice parameters.
Luke Lemons:
Exactly. And you may notice that this episode has a subtitle that says Curbside Consult. And in these episodes, we're going to be talking about a specific topic through the lens of a clinic or a practice. And so this'll feature discussions more around guidelines, the clinical impact of the topic we're talking about, as well as how it fits into a medical practice.
There will be other subtitles down the line, so if you see any other ImmunoCAST episodes with different subtitles, those are going to be around different themes.
Gary Falcetano:
Absolutely. So think of Curbside Consults as just that, a consult in the hallway between patients.
Luke Lemons:
So being that this podcast is about allergies, it makes sense that the first Curbside Consult episode is going to be about specific IgE testing, or allergic sensitization testing. And we're going to be talking about how providers can use this kind of testing to help diagnose allergies, as well as narrow their differential diagnosis. And we'll also be looking through some guidelines as well.
Gary Falcetano:
Yeah, exactly. It's a pretty broad topic, so we're really going to start with the basics and discuss the history of where allergy testing came from and how long we've been doing it and how it's evolved over the years.
Luke Lemons:
Can you tell us a little about the testing history for allergies, in general?
Gary Falcetano:
Yeah. Gosh, allergies have been described since the early Egyptians, but allergy itself really came into being around the early 1800s. And the first allergy tests were actually done in the late 1800s. An English physician, Dr. Blackley, actually used grass pollen, scratched his skin and noticed a reaction. And he was pretty suspicious that he had grass allergy. So he put two and two together and then did that with several dozen other patients of his. And that's really where the first allergy tests came from.
Luke Lemons:
That sounds a lot like skin prick testing.
Gary Falcetano:
So that's exactly what it was. It was a scratch test or a skin prick test. In the early 1920s, several other researchers also did that for both foods and then for aeroallergens as well. And it really became into regular use, skin testing became into regular use in the late 1920s, 1930s. But Luke, we went for 50 years and we didn't know what we were testing. We didn't know what was the molecule responsible for Type-1 hypersensitivity reactions. And I can guess ... I'll let you guess what happened 50 years later, in 1967.
Luke Lemons:
Well, wait. Okay, 1967. We discovered specific IgE, right?
Gary Falcetano:
Exactly, yeah. The last of the immunoglobulins to be discovered. So we'd already had I and G ... or I'm sorry. IgG, IgM, IgD. But they discovered this was a unique immunoglobulin and it was responsible for Type-1 hypersensitivity reactions. Interestingly, figuring out why we actually produce IgE ... and this is our fun fact for the day because we always like to have this. IgE is actually thought to really be protective against parasitic infections. And it's only when the body starts attacking things that normally it shouldn't, like pollens or foods, that we end up with allergies.
So that's where IgE and specific IgE being identified started. Shortly after 1967, the first in vitro blood test for allergy, or specific IgE was brought to market, and that was in the 1970s. An interesting fact is the researchers, some of the researchers that were involved in the discovery of IgE in '67 went on to convince a company to bring specific IgE blood testing to market. That company was Pharmacia, and also known as Pharmacia Diagnostics or Phadia. Thermo Fisher Scientific acquired Phadia in 2011. So we both work for Thermo Fisher. We've actually been involved in allergy testing since IgE was discovered in 1967.
And the test that is most commonly used to test for allergic sensitization looking at specific IgE is ImmunoCAP. And can you tell me the difference between a specific IgE test like ImmunoCAP and a RAST test? Because I know that a lot of times people say any sort of blood test looking at specific IgE is a RAST test.
Gary Falcetano:
Yeah, exactly. So a RAST test has really become a common name, although incorrect name for allergy blood testing. So the RAST test is a radioallergosorbent test, and that's actually where the testing started back in the 70s. It hasn't actually been a RAST test, at least ImmunoCAP hasn't, since the 1980s. So it's changed from a radioallergosorbent to an immunofluorescent test, which has made it a lot more sensitive. And it actually has clinical equivalency to the other types of allergy tests that we do on a regular basis or that specialists do, and that's skin prick testing.
So it's improved over the years with automation and increased binding capacity. And right now, the ImmunoCAP Specific IgE blood test is actually used in greater than 80% of the clinical laboratories in the world. It's really the defacto gold standard for in vitro blood testing for allergy.
Luke Lemons:
Yeah. You said that ImmunoCAP, or specific IgE testing is on the same level with skin prick testing when it comes to guidelines and recommendations on how to help diagnose an allergy. Can you talk a little bit about the difference between specific IgE testing and skin prick testing when it comes to how it's done, what patients can it be used on, et cetera?
Gary Falcetano:
Sure, sure. Absolutely. So as I said, they're both in regular clinical use. Skin testing is typically done by specialists, by allergists, but allergists also use in vitro specific IgE blood testing as well. They use them both interchangeably and in a complimentary manner, actually. The nice thing about specific IgE blood testing is it's not just limited to specialists. So it can be utilized by primary care providers, really anyone who normally orders laboratory testing can order a specific IgE blood test.
And there are some important differences between the two tests. And it really comes down to, one, I mean, the skin testing needs to be done by a specialist. Although it does have immediate results, so patients can see a visible result right after the test or within 15, 20 minutes. Blood testing takes a little bit longer to get the results, as you would imagine, going to a commercial laboratory. Some of the other differences, with skin testing, you have to be off medications that may interfere with the patient's response. So things like antihistamines. There are other medications that are potentially contraindicated with skin testing as well. Things like tricyclic antidepressants and beta blockers.
With blood testing, we don't have any of those contraindications. Both tests can be used in patients of any age with suspected allergy mediated symptoms. But with the blood testing, I think it's important to know that not only can it be done by any provider ... can be ordered by any provider. But also, it can be used really for any patient. So patients that are pregnant or extremely young age, it really doesn't matter. There aren't any contraindications to it.
Luke Lemons:
Also, when looking at patients who are going to get specific IgE testing, you mentioned that it can be done at any age. What is the youngest that a patient can get tested or blood drawn for specific IgE blood testing?
Gary Falcetano:
Literally it is any age. I think most clinicians will wait until about three months, until a child has developed really their own intact immune system. But there are investigations that are actually done on cord blood, so it can really be done at any age.
Luke Lemons:
Okay. And when it comes to guidelines as well, is there anything that providers should keep in mind or practice parameters around specific IgE testing?
Gary Falcetano:
Yeah, there's a whole slew. And I think depending on if we're talking about food allergy, if we're talking about rhinitis, in the different disease states is where we typically see these guidelines and practice parameters. One of the areas that we utilize specific IgE testing a lot, especially in primary care, is on the respiratory side of things, asthma, rhinitis. And there, on the asthma side, we have the National Heart, Lung, and Blood Institute, part of the NIH, as well as the CDC guidelines who both recommend testing for all persistent asthma. So anybody with persistent asthma symptoms should be tested for their allergic triggers. Then NIH food allergy guidelines also recommends specific IgE blood testing.
And then finally with rhinitis, there's a joint practice parameter. So there's two major organizations in the US, the American College and the American Academy of Asthma, Allergy, and Immunology, and they often publish joint practice parameters. And they have a recent practice parameter on rhinitis, actually, from 2020 that has a strong recommendation with a high level of evidence that recommends aeroallergen testing, whether it be skin or blood testing, to be completed to confirm the diagnosis of allergic rhinitis in patients. [inaudible 00:10:52] Yeah, go ahead. I'm sorry.
Luke Lemons:
Yeah. I was going to say, I'm glad you brought up rhinitis. Just because when a patient is exhibiting symptoms of rhinitis, it's often assumed that it's allergic rhinitis. And sometimes it's non-allergic rhinitis. I think it's 65% of patients who are prescribed antihistamines for allergic rhinitis, in fact, do not have allergic rhinitis. So that's a lot of people taking a lot of medicine that may not be helpful.
And so I think that there's also power in specific IgE testing to rule out the role of allergy. And we call it the power of the negative, right?
Gary Falcetano:
Yeah. Yeah, exactly. Testing has a very high negative predictive value. So when we get a negative, and especially if based upon the history we're sure we've assessed for the right potential allergens, we can be pretty sure that that's not what's causing the patient's symptoms. And as you said, up to two thirds of patients with chronic rhinitis symptoms are not allergic.
And I think in a lot of ways, we have empirically made the diagnosis of allergic rhinitis without actually any objective findings such as testing. And that's why the guidelines really recommend that testing be done in conjunction, of course, with history, to come up with a diagnosis.
Luke Lemons:
And so looking at results, you mentioned that some of the tests come back as, quote, unquote, "negative." What do results for specific IgE blood testing normally look like? Is it just numbers, is it a gradient?
Gary Falcetano:
The results are pretty straightforward. So as you mentioned, anything ... they basically have a range of 0.10 to 100. And anything in that range is considered a positive. And of course, the higher the level of antibodies ... so they're measuring the antibodies. The higher the level of antibodies, the more likely that that's the allergen or antigen that's causing the symptoms that we tested for.
Anything below 0.1 is considered negative or undetectable. And in that case, as I said, with a strong negative predictive value, these tests are very good at ruling out allergy, for sure.
Luke Lemons:
Can you give maybe an example, in your experience, when would you refer a patient, let's say to an allergist ... let's say you're primary care. And a patient comes in and you're suspecting allergies. You had mentioned earlier that specific IgE testing can be done in a wide variety of practices. So what would be the instance in which you would refer, and then what would be the instance in which you would do testing in primary care?
Gary Falcetano:
Yeah, so that's a great question. And I'm going to give you the second fun fact of the day. Luke.
Luke Lemons:
Oh, okay.
Gary Falcetano:
Did you know there's over 50 million Americans with allergic disease? It's actually the six leading cause of chronic illness in the US. And the reason I say that when you mention referral is there's about 4,000 clinically practicing allergists right now. So primary care really needs to obviously manage a majority of these patients, and then be able to optimally refer those patients that need the allergist's expertise.
So how this testing really can be used, anytime we have a suspected allergy-mediated disease ... and we can be talking about food. We can be talking about upper respiratory, like rhinitis, lower respiratory, like asthma. In any of those cases, phenotyping those patients first, so allergic versus non-allergic. And then once they're allergic, identifying what specifically is driving symptoms so that we can target that. And the number one treatment for allergy is removal or reduction of that causative allergen. And the second treatment is then medications, especially when we're talking about a respiratory allergy.
So I think it's important that primary care incorporate the testing early on with any of those patients. And then the patients that don't respond to exposure reduction or have a complex case or potentially need biologics or maybe candidates for immunotherapy, those are all great patients to refer on to the specialist, to the allergist to manage. But I think a majority of the patients certainly are managed and can be managed in primary care. It's important to really do our best job with them and give them the best possible information around their disease.
Luke Lemons:
How many fun facts do you have, Gary? I just saw you shuffling around when I was asking that question, reaching for papers. How many index cards you got hidden about allergies in that room?
Gary Falcetano:
You know what? There's so many fun facts in the head that I can't remember to pick up milk on the way home. So yeah, we'll have lots more in future podcasts for sure.
Luke Lemons:
You end up with dry cereal, but a lot of allergy knowledge.
Gary Falcetano:
Exactly.
Luke Lemons:
Well, back to specific IgE though, ordering these types of tests. Can you talk through a little bit about how to order ... I know that it involves different lab codes and all that. And I'm ultimately setting you up to talk about the lab ordering guide, which is something we're really excited to share with providers who are listening in right now.
Gary Falcetano:
Yeah. So as I mentioned, all the major labs offer the testing. A lot of regional and hospital labs offer it as well. And the way they offer it may be ... it's a little bit different depending on the different labs. So it's important to get familiar with the labs that you're working with. When we talk about respiratory allergies, what's typically recommended is ordering a respiratory profile. And that there's usually one that's specific to your geography.
The important thing to know about ordering a respiratory profile is that it's a very efficient way to order. So we're not going to order things we don't need. Luke, you're in New York. We don't have to order every grass tree or weed that grows in New York state. The ones that are on these profiles were selected by experts to be very representative through cross reactivity. So by ordering these profiles, it allows us to have a really nice negative and positive predictive value of someone with suspected respiratory allergy.
You mentioned the lab ordering guides, and I'll let you talk a little bit more about that. But it's really a nice feature that is offered in order to help people find out exactly where they're located, what labs are offering the testing, and what the codes are.
Luke Lemons:
Yeah. So like Gary said, a lot of different labs offer specific IgE testing. And these profiles are very important to use, for the reasons that Gary stated also. And so we've gone and created a hub of all these different profiles from all these different types of labs. It doesn't matter what lab you use, but if you're looking for a profile, a respiratory profile or a food profile, we have found all the best codes for you to use. And so if you go to thermofisher.com/laborderingguide and enter your zip code, it'll pull up all the labs in your area, or most of them. And then you can sort through to see, okay, this is the code for the most concise respiratory profile.
Because I've heard stories as I've talked to doctors in the past, that there is a ton of codes out there for a ton of profiles. And sometimes you're getting things you don't need, and other times you're getting not enough. I have spoken to providers who are ordering panels where they're just getting strawberry and some other berries, but this is a very concise guide to find the codes that you need to help you diagnose and better manage your patients. Do you have anything else to say on that, Gary?
Gary Falcetano:
No, I think I just want to discuss what the future is for our ImmunoCAST podcast. And it was important to set the stage around specific IgE testing on this first episode, but a lot of the topics that we're going to cover in the future will be more in depth on the different disease states, but we'll also be covering a lot of current research that's coming out, some more interesting facts as well.
And I'm just looking forward to having some additional conversations with you, Luke. And bringing our clinicians really the information that they need to better help their patients every day.
Luke Lemons:
Yeah, I'm excited to talk about some of the interesting topics that we were brainstorming about. I know we were talking about cockroach allergy and shellfish, because the shell is the same protein. There's a lot of interesting things when it comes to allergy. But if you're interested in listening to more ImmunoCAST, go to thermofisher.com/ImmunoCAST.
And if you go to this episode's specific page, you'll also be able to find resources, some practice parameters, and additional bits of information if you're interested in learning more about specific IgE testing. So thanks for listening in to the first episode.
Gary Falcetano:
Thanks so much. We'll see you next time.
Luke Lemons :
All right. Bye, everybody.
Announcer :
ImmunoCAST is brought to you by ImmunoCAP Specific IgE testing and Phadia Laboratory Systems, products of Thermo Fisher Scientific. For more information on allergies and specific IgE testing, please visit thermofisher.com/ImmunoCAST. Specific IgE testing is an aid to healthcare providers in the diagnosis of allergy, and cannot alone diagnose a clinical allergy. Clinical history alongside specific IgE testing is needed to diagnose a clinical allergy. The content of this podcast is not intended to be and should not be interpreted as or substitute professional medical advice, diagnosis, or treatment. Any medical questions pertaining to one's own health should be discussed with a healthcare provider.
