Patients with iodinated contrast media allergy have five-fold increased mortality risk
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Key takeaways:
- 53% of patients with an iodinated contrast allergy and 73% of controls received iodinated contrast injections.
- Deaths were attributed to delayed and unperformed imaging, not allergic reactions.
WASHINGTON — Allergy labels for iodinated contrast media were associated with increased mortality rates, according to a poster presented at the American Academy of Allergy, Asthma & Immunology Annual meeting.
These deaths may be due to delays in imaging and excessive corticosteroid use, but not due to allergy, Alon Y. Hershko, MD, PhD, chairman of the department of internal medicine C, Hadassah Medical Center, and colleagues wrote.
“We have a lot of patients who are labeled as allergic to iodine or contrast media,” Hershko told Healio.
When these patients arrive in the ED with acute problems such as stroke, Hershko said, physicians begin care by giving them pre-medications such as steroids or antihistamines because they are afraid that these patients will have a fatal allergic reaction.
“The problem is that some of these acute problems need immediate investigation,” Hershko said. “If you take a patient with stroke and you wait for 13 hours to give them steroids and antihistamine, the stroke is already evolving, and the damage has begun.”
To characterize the damage that labels for contrast media may have on these patients, the researchers reviewed data from 362 patients (median age, 71.6 years; 61% female) with documented iodinated contrast media allergy and from 341 controls with no allergy (median age, 62.2 years; 41% female) who were referred to imaging at Hadassah Medical Center’s Ein Kerem and Mount Scopus campuses between 2018 and 2022.
Hershko said that he and his colleagues discovered two interesting things.
“One is that if a person has a diagnosis of allergy to contrast media, they’re less likely to get contrast media when they do imaging. So that reduces the quality of the imaging,” he said.
The study indicated that 53% of those with an allergy and 73% of those in the control group received iodinated contrast media injections (P < .001).
“If a patient has a stroke, you want to see the blood vessels. Without contrast media, you won’t see a thing,” Hershko said. “When a patient has a stroke, time is brain.”
Specifically, among patients with stroke, 90% of those in the control group and 45% of those in the allergy group got a CT scan, according to Hershko.
There were similarly significant differences between the allergy and control groups for abdominal pain and malignancy. Differences also persisted for infection, trauma, vascular and other events.
The groups only saw equal percentages during cardiac events.
“The other thing is that they wait much, much longer for imaging,” Hershko continued.
Waiting times for studies involving iodinated contrast media injection included 2.7 hours (interquartile range [IQR], 1.2-14.6) for the group with allergy and 1.2 hours (IQR, 0.5-2.9) for the control group (P < .001).
Twenty-five patients (6.9%) in the allergy group and four patients (1.2%) in the control group experienced mortality events (P < .001). Sepsis (n = 14), cancer (n = 5) and stroke (n = 4) were the leading causes of death. There were no deaths due to allergic reactions.
“We saw five allergic events, and they were all mild,” Hershko said. “They were only limited to the skin.”
After adjusting for multiple covariates, the researchers said that iodinated contrast media was an independent predictor of mortality (OR = 5.54; 95% CI, 1.81-16.95; P = .003).
“When a patient comes in with pneumonia, the sooner you give antibiotics, the better the prognosis,” Hershko said.
Yet patients with pneumonia and an iodinated contrast allergy, for example, get lower quality imaging, and they must wait longer for imaging as well, he continued.
“Allergy is not dangerous. But the fear of allergy? That is what kills the patients,” Hershko said.
Hershko encouraged doctors who treat patients with these allergy labels who require acute care to request allergic consultations when they have concerns about allergic reactions.
In fact, Hershko said that he and his colleagues are now conducting a prospective study of the consultations that they are offering ED doctors. So far, he and his colleagues have provided 130 consultations.
“Whenever a patient comes in with an iodine allergy, we offer our consultation and we tell them that, if the risk of allergy is high or low, usually we advise them not to give any pre-medication and not to cause any delay,” Hershko said. “We still don’t have a single allergic adverse event.”
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For more information:
Alon Y. Hershko, MD, PhD, can be reached at alonh122@gmail.com.