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BackTable / VI / Podcast / Transcript #168
Podcast Transcript: Debunking Contrast Allergies
with Dr. Cullen Ruff
We talk with Dr. Cullen Ruff about common misconceptions when it comes to IV contrast and issues with the term "contrast allergy", including ways we can improve patient care and clinical workflows by clarifying the true source of these reactions. You can read the full transcript below and listen to this episode here on BackTable.com.
Table of Contents
(1) Defining Contrast Reactions
(2) Allergic vs. Allergic-Like Reactions
(3) Iodine Contrast Allergies: Common Misconceptions
(4) Importance of Documenting Contrast Names
(5) Specifying the Contrast Allergen
(6) Solution: Changing Patient Questions
(7) Only 1.6% of Patients Know Their Contrast Allergen
(8) Gadolinium-based Contrast Agents & Allergens
(9) Writing Dr. Ruff’s Book
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[Dr. Christopher Beck]:
Today we'll be talking about contrast and specifically allergic reactions to contrast agents. To help us with this discussion, we have now friend of mine, Dr. Cullen Ruff. Cullen is a diagnostic radiologist based out of Virginia, associate professor at the University of Virginia, and author of research papers and a book called Looking Within: Understanding Ourselves through Human Imaging. Cullen, welcome to the show.
[Dr. Cullen Ruff]:
It's great to be here. I'm happy to talk about this issue and hope that we can make all of our work a little more streamlined and efficient in the sake of patient care.
[Dr. Christopher Beck]:
We have a big vascular community with interventional radiologists, vascular surgeons, and also some diagnostic radiologists. Will you just tell us about your background training and kind of what your practice looks like right now?
[Dr. Cullen Ruff]:
Sure, I am a graduate of the university of North Carolina Medical School. I was Chief Resident at the University of Colorado. I did an abdominal imaging fellowship at Georgetown in Washington, D.C., and I have been with my current practice, Fairfax radiology centers for over 22 years, and that is the biggest private practice in the Washington D.C. area. We have three hospitals that we cover as well as 14 or 16 offices at this point. It's a big practice. It's 90 radiologists. And although I am not a vascular interventional radiologist, I do actually a whole lot of CT and ultrasound intervention, and this issue of contrast allergies has just become an interest of mine over the years because of some patient encounters, and then seeing what happens with the ordering of studies and the delay of studies being ordered or performed due to some misunderstandings about contrast. It's something that we all use every day, and there've been several important studies that have come out in the past few years, including a few that have come out in the past few weeks. And I'm really delighted for the opportunity to be here, to try to clarify what little I can so that we can all have a little more consistent understanding of the issues of contrast and allergies and prevention, and when we can and cannot do studies on people.
[Dr. Christopher Beck]:
That's great. Well, we really appreciate you coming on the show. Also I'd like to say that I did my fellowship at Georgetown. I was an IR resident, I think in 2014 and 2015, and I heard about the Fairfax group, big group. I remember just a little under a hundred guys and y'all were a force to be reckoned with and had a really great reputation in town.
[Dr. Cullen Ruff]:
Well, thank you, fortunately, I have been very lucky to be there because there are some very talented and smart people in my group. It's nice to have that degree of subspecialization, where you've got people who are sort of, reliable experts when you need something specific to go to.
(1) Defining Contrast Reactions
[Dr. Christopher Beck]:
No for sure. All right, so let's back up and just look at contrast reactions in general. So like the, the 10,000 foot views we call it sometimes, so let's just, for the audience, like define contrast reactions. Like, what exactly are we talking about with iodinated contrast reactions.
[Dr. Cullen Ruff]:
Okay. So again, we're talking about the iodine-based, iodinated contrast, which is used most commonly for vascular procedures, as well as for CT scans. And the contrast can occasionally induce an allergic-like reaction. And I want to say, well, we may say allergy for the rest of the podcast, but technically it's considered allergic-like, because it's not a true antibody immune type reaction, but it's more of a hypersensitivity. To be honest, the mechanism is still incompletely understood. It's speculated that it may be sort of immune cell mediated basophil or mass cell, but nonetheless people have allergic-like reactions. The most common ones being skin, whether it be hives or rash, some people will have a more serious reaction where they have shortness of breath. And then of course, more concerning, is if people start to have throat closure or an anaphylactoid reaction.
[Dr. Christopher Beck]:
Yes, I'll also echo that sentiment for the purists out there, we'll probably just say allergic reactions, but it's really allergic-like reactions or anaphylactoid reactions, because we don't know if it’s really IgG or IgE mediated, which is actually kind of surprising for the near ubiquitous use in radiology, and then, you know, also vascular and IR procedures, or anyone who's doing endovascular work. You would think we would just know so much more about it.
[Dr. Cullen Ruff]:
You would think so, but one inevitable and recurring reminder that I have is we actually don't know so much as we think we do about a lot of subjects, right? I mean, we don't have to go off on tangents, but we had men on the moon around the time the government was willing to acknowledge that repeatedly breathing tobacco smoke into your lungs is perhaps not a good idea. And we had smartphones around the time we understood the appendix has a purpose in our body in terms of being a reservoir for the healthy bacteria that we all need in our colon. So we have a lot of knowledge yet to go, and we're just doing the best we can. One year at a time.
(2) Allergic vs. Allergic-Like Reactions
[Dr. Christopher Beck]:
I can almost bet that there's probably a lot of our audience members, when you just talked about the appendix having a use, they’re like what is he talking about? But don't worry, we'll link to something in the show notes about the appendix, but we will push on. So now that we've talked about your defining kind of contrast reactions, can you talk about the difference between what some people may qualify as an adverse reaction to contrast versus like the allergic or allergic-like reaction.
[Dr. Cullen Ruff]:
Absolutely. So the older agents that were around for decades, the older ionic ones tended to first of all, be a little more allergenic, still a low percentage, but they also had a more common rate of having a physiologic symptomatic reaction, and that could be a feeling of warmth or flushing. Some people got nauseated, so it would induce vomiting sometimes. Those type of sensations, which are not pleasant, and I can understand why the patients might not want to receive it again, but those are not allergic-like reactions. They were simply side effects, physiologic reactions from the medication itself. Remember contrast is not a single drug, it's a drug class, and the non-ionic agents first started coming out in 1985, when the FDA first approved it, and if you don't mind my using trade names, just because it's what more of us are familiar with. I don't mean to be commercially biased, I'm treating them all equally, but Iohexol or Omnipaque was the first to get FDA approval, and then there have been several other nonionic, low osmolar agents or hyperosmolar agents come out since then, and these tend to be less allergenic and also better tolerated by the patient.
[Dr. Christopher Beck]:
Because I read your paper that you had sent to me, so 85 is kind of a cutoff point, would you say? So when you're talking to patients about their allergic reactions and they said, “You know what, Doc, I had an allergic reaction to contrast where XYZ happened to me in ‘75.” There's a big difference between that description and saying, “Hey, my throat closed up after had a CT scan last year.”
[Dr. Cullen Ruff]:
That's correct, because we know that if it was before 1985, that it had to be one of the older ionic agents that are not commonly used anymore. And in fact, even though the FDA approval happened in 1985, the use of ionics persisted well into the early two thousands because those agents were cheaper. And I know my own practice routinely used an old ionic agent until the early two thousands, until we finally realized let's just do the right thing, even if it costs a little more because it was better for the patients, and it was better for the workflow of the technologists. And gradually these, I think in most places, the old ionic agents have been phased out.
[Dr. Christopher Beck]:
Yeah. So that was actually one of my next questions. I know we can't speak to some places all around the world and not every practice, but is it safe to assume that in this day, maybe within the last decade, that if you're dealing with a contrast reaction, from a CT scan or something, that it's a non-ionic compound?
[Dr. Cullen Ruff]:
That's my belief in our country, yes.
[Dr. Christopher Beck]:
All right, so let's also talk a little bit about the range of allergic-like reaction you can have because I think there's anything from as severe as anaphylactoid, patients with difficulty breathing and airway compromise, to patients with developed hives a week after the contrast administration. Can you talk about the spectrum of which we can see allergic-like reactions?
[Dr. Cullen Ruff]:
Sure, well hives or some sort of rash that is the most common reaction. and it's usually not days later, it usually occurs within the moments after the injection. There can be delayed presentations, but most of the time it's going to be while the patient is still in the office. If that's all it is, and there are no issues with breathing, then that's considered a mild reaction, and the patient, is certainly eligible to have another injection in the future. But as we're going to get into, we'll talk about how you handle patients who have had prior allergic reactions. Less commonly you get into patients who have a little trouble breathing. There may be changes in blood pressure or heart rate, and then the most severe being the anaphylactoid throat closure.
[Dr. Christopher Beck]:
And I think it's also worth mentioning with adverse reactions that vasovagal reactions are fairly common, so hypotension, bradycardia can occur. And would you say that would be more common than these allergic-like reactions?
[Dr. Cullen Ruff]:
Oh, I think so. The allergic-like reactions vary depending on what study you look at.
[Dr. Christopher Beck]:
Right. It's hard to narrow down on exactly how common they are.
[Dr. Cullen Ruff]:
It really is, and part of that is, as we're going to discuss, because of the confusion about, contrast allergies that not only patients have, but their referring physicians and even technologists and radiologists.
(3) Iodine Contrast Allergies: Common Misconceptions
[Dr. Christopher Beck]:
Yeah, well, let's do a little bit to start like unwinding that. So what are some of the common misconceptions about contrast allergies or “iodine allergies,” and how do we tease that apart from just adverse reactions. And then, what I will set you up for later is then we'll go back and talk about, how we can talk about not just like contrast reactions as a class, but zero in on contrast reactions specifically to what agent you had.
[Dr. Cullen Ruff]:
Sure. Well, the way I like to start looking at this is a hypothetical scenario, which sounds ridiculous, but I think it brings home the point. Let's take one of the oldest antibiotics around and that's penicillin G. Back since the thirties or forties, if someone has an allergy to penicillin G, you put that in their medical record as a listed allergy. It would never occur to someone to say, “Well, they're allergic to antibiotics and you know what antibiotics contain carbon. Why don't we just call it a carbon allergy, even though that's not really the component of the molecule that they're allergic to, but let's just call it that for slang.” That sounds so ridiculous, but unfortunately that's precisely what we've done in the field, and this started long before you and I were born. When people, instead of calling the contrast allergen by name, lump it together as a class of contrast agent allergy, and then use slang of iodine, even though iodine is a component of the molecule, but not what the actual allergen is.
[Dr. Christopher Beck]:
So what is there about iodine allergies? Like when someone said that I have an iodine allergy, that's really a misnomer, right?
[Dr. Cullen Ruff]:
The term iodine allergy needs to be removed from our medical vocabulary, and there have been studies for years that have come out, disproving the claim of an iodine allergy. And in fact, only within the past week or two, since this podcast was already arranged, there was a really important study that came out, in the American Journal of Health-System Pharmacy that looked at 70 years worth of history and basically discredited any claim that iodine itself is part of the allergen. We know that iodine is a mineral that we all need to live. It's so important that it's put into our salt supply so that people don't have iodine deficiency. It's in every multivitamin that people are going to take. And iodine is a component of our thyroid hormone, which regulates our cellular metabolism. So we all need it to live. And therefore it's nonsensical to say that somebody can be allergic to it. And then the problem comes not just when you use the term iodine as a slang to refer to iodinated contrast in general, but people use the term iodine allergy to refer to at least two other things that are completely unrelated to contrast. One of those is iodine based soap, which people can have a skin allergic-like reaction to, but it's not to the iodine itself, it's a greater part of the molecule. And then the other term that people use is for a shellfish allergy. Some people still use the slang term iodine to mean shellfish, and I'm not really sure how that ever came about. But food allergies, whether it is shellfish, dairy, peanuts, or gluten, those tend to be protein allergies. And in case of shellfish, it's believed to be a protein called tropomyosin, but these allergies have nothing to do with each other. We don't, I don't mean to sound flippant or glib, but I've never worked in a radiology department that offered shrimp tacos after the CT injection was done. We're not giving people anything that is shellfish-based, and the Betadine soap and the iodine based soap is unrelated as well. Which is why I think the term iodine allergy needs to actively be removed from all medical vocabulary and from electronic medical records as a valid allergy choice.
[Dr. Christopher Beck]:
And so also, just touching back about that shellfish allergy, just to unwind that a little bit more. So if someone has a shellfish allergy, I think this is pretty commonly known, but you can never be sure. If you have a shellfish allergy, it doesn't even predispose you to an allergic reaction to contrast materials, right?
[Dr. Cullen Ruff]:
That is correct. So one of the best references is the ACR American College Radiology Manual on Contrast Media, which everyone can access online and it's updated just about every year. It's an excellent resource, has a lot of good references and that manual on contrast media has followed this policy for some time. You don't take anybody with a reported shellfish allergy and treat them any differently with regard to a contrast injection, as long as they've never had an actual contrast injection, you treat them the same as everyone else.
[Dr. Christopher Beck]:
Got it. And the same thing with Betadine. So if someone's said, “I had a surgery a year ago, they used Betadine. It broke me out terribly.” You still treat that person with the same risk profile as someone who has had no reactions to iodinated contrast.
[Dr. Cullen Ruff]:
That's absolutely correct. They're unrelated substances. They have nothing to do with each other.
(4) Importance of Documenting Contrast Names
[Dr. Christopher Beck]:
Okay. So if we think iodine allergy should be removed, what should we be telling patients when they have an allergic reaction? So we'll go back to a scenario where a patient has an allergic reaction to a non-ionic or a recent contrast allergy, like during a CTA or whatever. What should we be telling that patient? Or what should we, as the physicians or some of the technologist, what should we be documenting?
[Dr. Cullen Ruff]:
The first thing you document is the actual contrast agent given by name, just like you would any antihypertensive or any antibiotic or any other drug that a patient has an allergic reaction to because what's most important is the next time this person needs a contrast injection, you can give them something different. We'll use penicillin G as the rogue antibiotic example here, if someone's allergic to penicillin G, and they need an antibiotic, what makes more sense to you: to give them the antibiotic that they're allergic to plus steroids to premedicate or does it simply make more sense to give them a different antibiotic that they've never had? And that's what we're going to discuss here. That's the same thing when it comes to contrast, we have to know by name what people have reacted to so that we can give them something different because giving people a different agent is the best way to prevent a future reaction much more so than steroid pre-medication.
[Dr. Christopher Beck]:
Another scenario, so if a patient has an allergic reaction and I'm going to use trade names as well, like Omnipaque 350, then if that patient comes back, having had a documented allergic reaction, you would recommend as the radiologists that, “Hey, let's try something different, like ISOVUE or Visipaque.” Is that right?
[Dr. Cullen Ruff]:
Absolutely. So ISOVUE, Visipaque, Optiray, Omnipaque, those are some of the most commonly used current low osmolar and lower allergenic agents. And yes, you would simply choose a different one.
[Dr. Christopher Beck]:
And if you had that patient to see, like say you knew that they were coming in ahead of time, what about the pre-medication protocols?
[Dr. Cullen Ruff]:
I think it depends on the severity of the reaction. Although I will say the latest studies that have come out have actually shown very little to nearly no benefit with steroid premedication in the patients who have had the most severe reactions. So there've been some other studies that have said, and I think this all depends on the study design: there's always going to be some inherent differences in terms of who's included, who's excluded how the data is looked at. There have been other studies that have shown that a steroid pre-medication in addition to changing the contrast agent given, is even more effective than changing the agent, but changing the agent is the most important component, more so than the steroid pre-medication.
[Dr. Christopher Beck]:
Right. And it's fair to say that, I know that my practice mirrors this, we put a huge emphasis on the steroid premedication protocol, and we rarely talk about changing the agent, but that's why I was so interested in having you on because that really needs to be the discourse about changing the agent, focusing on what they had an allergic reaction to, and then using something slightly different.
[Dr. Cullen Ruff]:
That's right. And what we'll talk about on our show here is the fact that it's hard to know what the patient was allergic to because the focus of our study was to see just how little the patients with a contrast allergy know about their own allergy. And unfortunately their knowledge is quite limited and there is a large opportunity for us to not only educate ourselves, the radiologists and the technologists, but definitely the patients and their referring, ordering doctors.
[Dr. Christopher Beck]:
So if you had it your way, so if you had your druthers and you had full control over the radiology department, which for all I know maybe you do at a couple of your hospitals.
[Dr. Cullen Ruff]:
I most definitely do not. I think the first thing I'd do would give myself a day off a week.
(5) Specifying the Contrast Allergen
[Dr. Christopher Beck]:
Clearly we've mentioned that we need to be documenting the exact agent that's being used. So no longer contrast allergy, certainly not iodine allergy, but contrast allergy and specifically allergic reaction to ISOVUE. And then after that also would recommend like the techs, nursing, and the radiology staff would recommend or would document the type of reaction severity. What else?
[Dr. Cullen Ruff]:
Well, those are the most important things. So again, knowing what the patient had and reacted to so that you can use something different, understanding the severity of the reaction. If the patient's allergy was remote and they don't remember when or where it occurred, then you have to do the best you can. So again, if you know, it was before 1985, it was basically certainly an old ionic agent. If it was somewhere between that period and the early two thousands, you may have to dig because a lot of people were still getting older ionic agents. And you have to try to do the best you can with regard to old record obtaining. The patients, I can tell you, the patients are usually not going to know as well as we'll discuss with my own study, but it's one of these changes we all have to make in order to make it better next year, even though it may be a little cumbersome right now.
[Dr. Christopher Beck]:
Right. So there's some backup work that we have to do with existing allergies. So there's a little bit of unwinding that we really have to do in terms of patients who come to the radiology departments and say, “I have an iodine allergy,” right?
[Dr. Cullen Ruff]:
That's right. But there are things we can do to make the situation clear and more efficient for everyone. You first do need to tease out what do they mean by that because again, that can mean at least three different things, depending on whom you ask. So that may mean a contrast allergy, it may mean a Betadine or an iodine soap allergy, or it may mean shellfish allergy. So first you try to distinguish what the people are talking about. When you can remove the food allergies and the topical soap allergies, then you just focus on the intravenous contrast allergies, and if you can't whittle it down any better, you can at least say, rather than saying that someone's allergic to iodine, at least specify that it was some unknown iodinated contrast agent. If you know it was before the mid eighties, then you can even add further that it had to be an old ionic agent, but you do the best you can.
[Dr. Christopher Beck]:
And I think that's one of the things that we had pushed back with our techs, we thought about taking out iodine allergy from the Epic dropdown list. And not that the techs were opposed to that, but their argument was that they now understood that you can't have an iodine allergy, but a lot of these patients, who were uninformed were using iodine allergy as a way of talking about that they had a reaction to CT contrast dye, and so I think that it is just the labor or the work of going through and spending time with the patients to really tease apart what exactly they had a reaction to.
[Dr. Cullen Ruff]:
Well, but there are things that we could all do that would be a little more efficient. First of all, some of these changes or implementations we're making in my practice, this fall based on our own paper and some of these other studies. We want to have all this information available on our website. We want to make it available to patients when they're scheduling ACT procedure or a vascular interventional procedure. And we are planning on mailing out something to all of our referring docs, explaining the differences. Let me just give you a scenario, something that actually happened. We had a case in going through all the data, I found at least one case where the technologists called the covering radiologist and said, “The patient has never had contrast, but had an anaphylactoid reaction to shellfish.” The radiologist made the decision, which was unfortunate of saying, “Well, go ahead and withhold the contrast just to be safe.” Well, that patient was now had their contrast withheld. When they came to us, that patient will probably never consent to getting IV contrast unless they have a whole lot more education because this radiology practice withheld it. But it's not just that one patient, their doctor now knows that we withheld contrast on someone with a shellfish allergy, and therefore the doctor may never order a contrast study again on anybody with a shellfish allergy. So you have to look at the broader picture here. The changes have to occur in order to get the right patients, to having the right study, and to not have these delays in care, which include delaying the study because people may be getting unnecessary steroid premedication, which takes hours.
[Dr. Christopher Beck]:
Actually one of the things that I think that the ACR manual references is that the pre-medication protocols in and of themselves are fairly low risk. And I think that's one of the reasons they continue to persevere is that, oh, what's the downside, right? You're talking about three doses, maybe two doses of steroids about half a day before you receive your contrasted study. But I think like the real downside with the pre-medication protocols is that there can be a delay in patient care and added cost to the patient. It's one more barrier to entry that can already be kind of a daunting process for just like the layperson.
[Dr. Cullen Ruff]:
All of that is true, but the other downside is the pre-medication does not work.
[Dr. Christopher Beck]:
Oh, yeah, I guess I should've mentioned that, but you did mention that there’s no real good evidence that it works and certainly no good evidence that it works for the people who are at the higher risk for having a bad reaction.
[Dr. Cullen Ruff]:
That’s right.
(6) Solution: Changing Patient Questions
[Dr. Christopher Beck]:
So it seems like you guys are making some changes to your practice. I mean, some real world changes to the practice. Are there any other changes? I mean, you mentioned a handful. Are there any other changes that you guys are implementing that you think is appropriate that more people can kind of glom onto? And, I think that one of the struggles with radiology, especially something like this is that there's so many things to keep up with. Technology is advancing. Our understanding of disease processes is advancing. We're looking at the same diseases with different modalities that there's so much to keep up with. And then someone's like, oh, and you have to be an expert on contrast allergies. What are some things that like people can implement in their practice that can help unwind this that are some low hanging fruit?
[Dr. Cullen Ruff]:
Well, one thing that we already did several years ago has worked out very well. And that was to change our patient questionnaire. When I came to the practice and for, well over a decade into it, the old patient questionnaire that someone else wrote out, asked the question: are you allergic to iodine? And once I started doing the research on this issue and realized that that term was nonsensical and confusing the issue and not good for patient care, I changed the questionnaire with the approval of the practice. So we changed that term from are you allergic to iodine to are you allergic to iodine-based contrast? And what we found was there was no increase in allergic reactions in the offices. So nothing bad happened from it, but I then did a study that I haven't published in print, but I did present at the ACR Annual Meeting of Quality and Safety last fall. And we found that the technologists had the opinion that changing that questionnaire, just the terminology wording, made their patient prep for CT studies more streamlined and faster because by asking a more targeted and accurate question, are you allergic to intravenous iodine-based contrast, it was clear for the patients to answer, and we don't ask any more about shellfish or other non-related allergies.
[Dr. Christopher Beck]:
So this is a question that's a little bit specific to IR, and I apologize for not including it on the outline, but it just occurred to me. If you have a patient who has had a reaction to a recent non-ionic contrast material, like Omnipaque, and then you have them for a vascular or a nonvascular procedure, like a body procedure, those patients are still at risk for an allergic reaction. If you inject this, say for an epidural or an epidural steroid injection or a gallbladder drainage or if you're doing a nephrostomy tube, is that right? Or am I off there?
[Dr. Cullen Ruff]:
The less of the agent that's getting into the bloodstream typically means the less likelihood of a reaction.
[Dr. Christopher Beck]:
Okay. Less likelihood, but maybe you're still at risk, but still less likelihood?
[Dr. Cullen Ruff]:
Yes, I don't know that anybody would say absolute zero, but it has to be less if it's not getting into the bloodstream where the immune reaction or allergic-like reaction might occur.
[Dr. Christopher Beck]:
Okay. That makes sense. but like what we're advocating here or what you're advocating is that if you do have a patient who's allergic to a specific contrast agent then simply switching the agent is what needs to be the standard protocol. And is there a paper to back that up with the research to back that up?
[Dr. Cullen Ruff]:
There are several, and I have a few actually written down in front of me because I used these as references for my own study that has just come out in Clinical Imaging. So I'm just going to give you a few, again, most of these are in the ACR Manual on Contrast Media, but then there are a couple new ones. So there are several, and most of these are in the ACR Manual of Contrast Media references. And I've written a few out just as some examples. I have: Abe et al., European Radiology, 2016 and Cha et al., Radiology, 2019. There were two studies by different doctors, each named Park et al.: one was in Radiology 2018 and one in European radiology, 2017. And then there was a study that just came out in August of 2021 from Mayo Clinic, McDonald et al., and that was in Radiology. And that also showed that changing the agent is much more useful than steroid pre-medication.
(7) Only 1.6% of Patients Know Their Contrast Allergen
[Dr. Christopher Beck]:
Awesome. And what we can do also, Cullen, is I can link to those articles for those who want to take a deep dive into this topic, and we've already referenced the ACR manual, which is free, and we'll also post links to all the articles that we just referenced. So for those who really want to do a deep dive, there'll be in the show notes usually a week later. You know how we're not super diligent about getting our show notes out, but usually we're about a week out from production. So, Cullen, another thing I wanted to ask you now, along the vein of research, can you give the audience the crux or the bullet points to the paper that you recently published?
[Dr. Cullen Ruff]:
Absolutely. I'd be honored to. So because the subject has become such a clinical interest of mine, we did our own study because again, you asked why is it that we're going to have trouble making the changes that we need in terms of labeling contrast allergies by name. And it's always been my unquantified perception that patients know very little about their own contrast allergies and much less than they know about other medication allergies in general. And so that was what we looked at. We did a keyword search within our database and came up with a cohort of over 300 patients who have a confirmed contrast allergy, and we ask them some simple questions. The patients were very good at being able to describe their symptoms. So 87% of the patients with a prior allergy could describe the symptoms. And we removed the people who described symptoms, just like flushing, nausea, and vomiting. We didn't count those because we knew that those are just physiologic, but out of people who had more of a confident contrast allergy, the patients were great at knowing their symptoms equal to other studies that are in pharmacology literature. But we asked the patients, “When did your allergy occur?” Because that's important to know. If they know when their allergy occurred, that helps us determine if it was one of the older agents or one of the new. Only 37% could estimate the year when they had their reaction, and an additional 7% said a long time ago, and about 57% just could not estimate when it had happened. Then we asked them, “Where did your reaction occur?” And we would take either the city and state or the name of the hospital or clinic, just to be inclusive. But only about 40% of the people could tell us where, and 60 could not. And so that obviously tells you, you're not going to be able to get the old records the majority of the time. If these people can't tell you, and again, our study was done on outpatients and a private practice, most of whom are coming in walkie talkies. They either speak English or they have someone with them who does. So it would be even worse if you were talking about people coming into a hospital emergency room who are more acutely ill and less able to answer these questions. Then came the main question, which was can you tell us the name of your contrast allergy. Now, other studies in pharmacology literature have estimated that before counseling with a pharmacist, patients are about 60 to 70% accurate in being able to name their drug allergies. And after counseling with the pharmacist, patients are maybe 80 to 95% accurate in terms of knowing their own allergies. But when we asked patients, can you name your contrast allergy? Would you care to guess what percentage could?
[Dr. Christopher Beck]:
25%.
[Dr. Cullen Ruff]:
1.6.1.6% of patients who have a contrast allergy, were able to say which one it was, and we've just got to do better than that because if patients don't know, then we're not going to be able to give them something different. Because there were so few, five out of 307 patients, who knew what they were allergic to, I even called them.
[Dr. Christopher Beck]:
You called the five patients?
[Dr. Cullen Ruff]:
It was a short list. So I called them, and I said, “Why is it that you knew when most people did not?” And the answer that I got repeatedly was when I had my reaction, the technologist or the radiology, told me what I had been injected with, and they gave it to me in writing.
[Dr. Christopher Beck]:
Wow.
[Dr. Cullen Ruff]:
So you asked what are changes people can do. That's one of the things we're going to do every time we get a patient back into our practice, who's had a reaction, whether it's a new one today or a previous one, our goal is to print out for the people, what they reacted to. We want them to list this on all of their medical records by name and that way we'll know what we can avoid in the future and give them something different.
[Dr. Christopher Beck]:
Have you guys worked with your EMR of choice, whether it's Epic or Cerner, to add the names of the contrast agents, like the specific contrast agents to help with documenting contrast allergies?
[Dr. Cullen Ruff]:
The specific contrast agents are choices within the electronic medical records. We also use Epic. And if you want to type in that someone has an allergy to Omnipaque, ISOVUE, Optiray, Visipaque, or whatever, you can do that, it's just that most people haven't narrowed that down. So the choices are there. The work that we need to do is to work with Epic or whichever EMR system to have them not offer iodine as a choice because, as we've discussed, that's a nonsensical term that we don't want to encourage people to use. And we want people to be more selective and specific. So if that is a previously existing allergy, maybe there could be some dropdown choices to narrow it down, whether it's a contrast agent or something unrelated like topical iodine soap or shellfish or something else.
[Dr. Christopher Beck]:
That's great work that y'all are doing. How long have you guys been documenting the exact contrast agent in the EMR?
[Dr. Cullen Ruff]:
Oh, when I say, we, this is not consistent at all. So it's something that I've started doing because of the research we've been doing, but the more, comprehensive approach is something we're just starting in the outpatient practice. And it's going to take more time and more effort at the hospital because there are so many more people who use the system.
[Dr. Christopher Beck]:
Of course. Yes, sometimes it's as much about education and outreach. There's only so much one person can do, so good luck fighting the good fight.
[Dr. Cullen Ruff]:
Well, thank you. It's going to be an uphill challenge, but it's in the patient's best interest and it's in our best interest too because it makes the workflow more efficient for the technologists and the radiologists, where every time a patient may have an allergy, and everything comes to a grinding halt because you have to answer these questions for the umpteenth time. I think if people realize we're doing ourselves a favor by being accurate, then I'm hoping that the pattern will pick up.
(8) Gadolinium-based Contrast Agents & Allergens
[Dr. Christopher Beck]:
Absolutely. So let me take a little bit of a left-hand turn and instead of talking about iodinated contrast, we talk about some MRI or gadolinium-based contrast agents, so specifically not as much with allergic reactions, although I think that you can have an allergic reaction to MRI contrast agents. Can you speak a little bit about how often this occurs?
[Dr. Cullen Ruff]:
It is less common. The literature, again, a source like the ACR’s Manual on Contrast Media can be specific with regard to larger studies. I know that in our study where we had a cohort of over 300 patients with an iodinated contrast allergy, only four people we had to exclude because they actually were not allergic to an iodine-based contrast but claimed to be allergic to a gadolinium-based contrast. But what we did notice was not one of them specified Gadavist, Magnevist, Eovist, or whatever. The best they could say was gadolinium, and we know from the research that knowing which gadolinium-based MRI agent people have had is important, because some of these agents are more prone or less likely to cause conditions kind of like nephrogenic systemic fibrosis. So we started out using MRI contrast with impunity, not worrying about renal failure, et cetera, then realized that there are a few patients that are actually showing this condition. It's not common, but it's serious when it happens. And now that people have paid a little more attention to which agents cause it, it allows us to avoid having that, and maybe again, start injecting with impunity as long as we use agents that don't cause this condition.
[Dr. Christopher Beck]:
So that's a little bit telling of how long you've been out in practice Cullen, that you were part of the age when if someone was allergic or had allergic contrast or had renal insufficiency that you guys would just do contrasted studies with MRI.
[Dr. Cullen Ruff]:
That's absolutely right. We didn't care what their renal function was until we learned the hard way that it was important for some patients receiving some contrasts agents.
(9) Writing Dr. Ruff’s Book
[Dr. Christopher Beck]:
All right. And predictably, now the pendulum is starting to swing back and that, NSF, so certainly serious, uncommon, but when it does happen, it can be quite debilitating. Well there's still one more topic that I would be remiss if we didn't dive into a little bit. Will you tell me in the audience a little bit about what it was like writing the book, Looking Within: Understanding Ourselves through Human Imaging. So specifically, I just want to know how hard was it to actually write a book?
[Dr. Cullen Ruff]:
Oh, it's an interesting question to answer. It was not hard in terms of being motivated at times, because whenever an interesting case would happen, whether it be interventional or diagnostic, and there were both. I’ve got stories of angiograms gone wrong, biopsies, et cetera. And also just intriguing diagnoses made from x-rays CT, and other studies. It wasn't that hard to say, “Wow, this is a really interesting case. There's something we can all learn from this.” I don't just mean radiologists. I mean the public in general, but getting a book completed and getting it published and into print, it's actually quite time consuming with a lot of turns and detours and challenges. And I'm glad I did it, but it's not something that people should do for the money because I don't think I'll be retiring one day earlier based on this book. But it was rewarding to write something that other people have read and say, “Hey, I really enjoyed this. I got something out of it. I think I understand your field a little better. I never knew this about radiology, and that's been rewarding.”
[Dr. Christopher Beck]:
So out of curiosity, how long did it take you from starting the process to getting something out where you sold a book. What was start to finish?
[Dr. Cullen Ruff]:
I'm embarrassed to tell you, Chris, but I will answer the question. Keep in mind there were long periods of time in the process where I was doing nothing with it. I would write for a while, and a lot of times when I would write, would be say on a vacation, sometime when I had the time to do it because most of our workdays are busy enough. The writing was one thing, getting a literary agent was another. Then having her trying to find a publisher was another. And there's a lot of waiting while you get an agent while you get a publisher. Ultimately, the agent I had was a very good one in New York, but she was not able to get me a big publisher and that's all she deals with. So then it came time to find a smaller publisher, which also took time. Start to finish to answer your question, it was well over 15 years.
[Dr. Christopher Beck]:
Wow. But how did it feel when you sold your first couple of copies?
[Dr. Cullen Ruff]:
It was exhilarating because we know if you've ever gone over a study with a patient or a family member, you see that fascination when people look at the images and say, “Wow, that's what I look like on the inside. Or I never knew you could tell this about a person.” And it's not just the anatomy and the disease. When you look inside of somebody, it's kind of like having a crystal ball sometimes. You're looking into someone's past or their potential future, given what their condition is. And so there's a lot we can learn. I've read other books by other physician authors, and these were quite good. Everybody from neurologists, surgeons, ER doctors, internists, but I had never seen one by a radiologist. That’s what motivated me to write it because I know we have an interesting field, and I just wanted to get some stories out there. Each chapter is a patient story that just shows something interesting. And the beautiful thing about my book is it's got pictures.
[Dr. Christopher Beck]:
That's right. Of course. Picture heavy.
[Dr. Cullen Ruff]:
It's been fun. I appreciate your asking. Again, I'm not planning on retiring any earlier from this book, but the reviews were good enough that Amazon made the book a daily special earlier this year on their digital version. And so it was really gratifying, even though it was so discounted that I didn't really make anything. It was really gratifying. Well, it's true. But, to know that in one day nearly a thousand people bought it. It was humbling, and I just tell people to enjoy reading it.
[Dr. Christopher Beck]:
I think that's really great. One, I think it was so beautifully put how, and I never thought of it like that, that reading a radiology study, it’s in a certain way, looking into someone's past and a certain way of looking into their future. And I have to admit, I think we take it for granted, but it can be a really special experience for going over that with a patient. I think some people have practices, and we even have a form of this, where we have some executive wellness programs where we go over the imaging with some of the patients and like kind of walk them through what we're seeing and they love it. They're just fascinated by it. They could sit at the viewing station all day and just keep asking questions, like, “What is this?” And so I think that's really neat to shed some light on such a great specialty that we have and bring it to the public. Fantastic. So, as an ambassador to the radiology practice, thanks Cullen.
[Dr. Cullen Ruff]:
Oh, my pleasure. I really appreciate your interest.
[Dr. Christopher Beck]:
All right. So if you don't mind, we'll include a link to that, to whatever way is easiest to purchase it, whether it's Amazon or whether it's giving people the address to your house so they can come by and pick up a copy. We'll make sure we link to it in the show notes.
Podcast Contributors
Dr. Cullen Ruff
Dr. Cullen Ruff is a practicing diagnostic radiologist and associate professor in Virginia.
Dr. Christopher Beck
Dr. Chris Beck is a practicing interventional radiologist with Regional Radiology Group in New Orleans.
Cite This Podcast
BackTable, LLC (Producer). (2021, November 26). Ep. 168 – Debunking Contrast Allergies [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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