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November 13, 2018

On the Front Lines of Anaphylaxis: Using Data to Save Lives

By Advancing the Science contributor

By Ronna Campbell, M.D., Ph.D.;  Megan Motosue, M.D.; and M. Fernanda Bellolio, M.D.; Mayo Clinic

Anaphylaxis is a serious, potentially life-threatening allergic reaction that affects millions of Americans. Today, nearly 15 million people in the U.S. have a food allergy and numbers are increasing.

Symptoms of anaphylaxis can occur within seconds following exposure to an allergen such as a medication, food, or an insect sting. This triggers an immune system response that can cause hives, itching, nausea, vomiting, diarrhea, narrowed airways, difficulty breathing, and may decrease blood pressure causing dizziness and loss of consciousness. Immediate treatment is critical.

As Mayo Clinic emergency department (ED) clinicians, we work on the front lines of treating anaphylaxis and wanted to know whether there were ways to better treat anaphylaxis, including preventing reoccurring ED visits.

To answer our questions, we conducted several studies on national trends in anaphylaxis-related ED visits and outcomes using the OptumLabs data, which includes de-identified claims for privately insured and Medicare Advantage enrollees over many years. Our research is helping us to improve anaphylaxis prevention and treatment protocols at Mayo Clinic, with potential to help the millions of Americans who suffer from this potentially deadly reaction.

Trends in anaphylaxis-related ED visits and outcomes

Overall, we’re seeing increased instances of anaphylaxis among younger people caused by food (nut allergies) and by medications taken by older people, especially those who have complex health conditions. The rising cost of injectable epinephrine, the primary treatment for anaphylaxis, is also concerning because it is making it more difficult for some patients to access the proper tools for management.

Using the de-identified OptumLabs data, we evaluated trends in anaphylaxis ED cases across three categories: the most common triggers, risk factors for severe cases, and prevention. Here’s what we’ve found:

1.  Anaphylaxis is increasing and is frequently caused by food, medications and venom.

Looking across 56,212 ED visits in claims data for patients of all ages, we reported in the Journal of Allergy and Clinical Immunology: In Practice that rates of ED visits for anaphylaxis doubled between 2005 and 2014 (14.2 per 100,000 to 28.6).

Anaphylaxis ED visits doubled between 2005 and 2014

Line graph shows anaphylaxis ED visits per 100,000 enrollees doubled between 2005 and 2014.

The most common allergic reactions were due to medications, food, and venom (by way of stings from bees, wasps, yellow jackets, hornets, and fire ants). There was another large category of unspecified triggers, which may be cases where the allergen could not be identified in the ED or the diagnosis was not entered as a claim.

We also found that anaphylaxis cases were excessively high in children 5-17 years old, mostly due to food allergies. We reported in Pediatric Allergy and Immunology  that among 7,310 children, ED visits for food-induced anaphylaxis more than tripled (6.40 per 100,000 to 20.05) from 2005 to 2014. Peanuts were the leading cause, while ED visits related to tree nuts and seeds had an almost a four-fold increase. Other studies have found that food-related allergies now impact 1 in 13 children, an average of two students in a typical classroom.

2.  Anaphylaxis severity is increasing and patients who are older, have chronic disease, or have medication allergies are most at risk.

Looking across the 56,212 ED visits for patients of all ages with anaphylaxis, we reported in the Journal of Allergy and Clinical Immunology Practice that over time more people were admitted to the hospital, placed in the intensive care unit (ICU), or underwent endotracheal intubation(placement of a plastic tube inserted through the mouth to carry air to the lungs) for treatment, suggesting that severe anaphylaxis cases may be increasing.

To understand why, we looked at the characteristics of the 38,695 patients who had these severe cases of anaphylaxis. We reported in Annals of Allergy and Asthma Immunology that the most common patient risk factors were being 65 years or older, having multiple health conditions (particularly heart or lung disease), or an allergic reaction to medication.

Odds of experiencing severe anaphylaxis by most common patient risk factors

3.  Many patients do not get epinephrine or see an allergist to prevent and manage future reactions.

We also wanted to know what patients were doing once they left the ED to help prevent and treat potential future incidents. National guidelines recommend that all patients who are treated in the ED for anaphylaxis receive and fill a prescription for injectable epinephrine — e.g. commonly known by the brand name EpiPen, but includes other brand names: Adrenaclick and Twinject  ― and follow-up with an allergy/immunology (A/I) specialist. But the preventive follow-up isn’t happening for many.

We reported in the Journal of Allergy and Clinical Immunology: In Practice that among 18,279 patients of all ages who were discharged after an anaphylaxis-related ED visit, only 46 percent filled a prescription for injectable epinephrine and only 29 percent had an A/I follow up within one year of the ED visit. This suggests that many patients may not be prepared to manage future episodes. Additional efforts are needed to identify system-based and patient barriers to guide strategies for improvement.

Rate of preventive steps after an anaphylaxis ED visit among patients

Graph shows for every 10 people, 2.9 see an allergist and 4.6 fill an epinephrine Rx after the ED.

We need to do more research to determine whether the issues lie largely in patients not receiving a prescription for injectable epinephrine, or whether many patients are just not filling their script. In light of escalating costs of these devices, it will be important to examine the patient out-of-pocket costs (co-payments, co-insurance, and deductibles) that may be barriers to filling prescriptions. Recent FDA-approval of the first generic version of injectable epinephrineand extension of the expiration dates by one year are two important steps in making this preventive treatment more accessible to patients who need it.

Among those patients who filled an EAI prescription within a year, most (58 percent) did so within one day of discharge. The immediate days after discharge — when patient awareness is heightened after being very sick in the ED ― is an important window of opportunity for prevention-targeting interventions.

How we’re using this data to improve clinical practice

At Mayo Clinic, we use a multidisciplinary approach to improve how we work with those at risk of anaphylaxis by 1) appropriately observing patients, 2) educating our staff about anaphylaxis prevention and treatment best practices, and 3) preparing patients with the knowledge and tools to prevent future events once they leave the ED.

Here’s what we’ve done based on our research and experience:

  • Created an observation unit protocol. Sometimes hours after the symptoms of anaphylaxis clear, patients may experience biphasic reaction, or a second onset of anaphylaxis. Our protocols make it easy for clinicians to keep patients in an observation area to monitor for recurrent symptoms, and avoid more costly hospital admissions. We’re currently doing research with our patients to better understand who is at risk for these rare but serious reactions so that we do not keep anyone longer than needed.
  • Recruited nurses to provide training. All of our nurses are trained to teach patients how and when to use injectable epinephrine. This takes some of the burden off ED providers and better prepares our patients to safely manage their allergy once they leave the ED.
  • Ensured patients have a referral to an allergist. Our ED providers are trained to refer all patients to an allergist so they can learn more about their allergy and how to best treat it.

Another study that we conducted using OptumLabs data highlighted the importance of arming patients with clear and actionable information after visiting an ED, especially those with a food allergy. Patients who had anaphylaxis due to a food trigger were more likely to return to the ED to be treated for anaphylaxis, as were those who had a history of asthma or had a more severe initial reaction requiring admission to an ICU. That’s why it’s particularly important that these patients understand how to prevent and treat future reactions.

Unfortunately, as the rates of allergies and asthma continue to rise, the demand for treatment also grows. Using data and research, we will be able to help improve access and quality of care delivered to people suffering from these awful conditions.


  • Ronna Campbell, MD, PhD, is an emergency medicine physician at Mayo Clinic
  • Megan Motosue, MD, is an allergist at Kaiser Permanente (formerly a fellow at Mayo Clinic)
  • M. Fernanda Bellolio, MD, is an emergency medicine physician at Mayo Clinic
  • This post was edited by Samantha Noderer, MA, communications and translation manager at OptumLabs


This article was originally published on the OptumLabs blog. OptumLabs is a research collaborative cofounded by Optum and Mayo Clinic in early 2013.

At its core is a rich, highly curated data set of over 200 million de-identified lives containing linked data from administrative claims, medical records and self-reported health information. This gives real-world insights on individuals' complete health experience.

Pairing administrative claims with unique details on patient and health plan actual costs, demographics, health behaviors and more, researchers and innovators use OptumLabs data to look at long-term trends and understand the value of care.

Tags: anaphylaxis, Center for the Science of Health Care Delivery, emergency department, emergency medicine, M. Fernanda Bellolio, Megan Motosue, News, OptumLabs, Ronna Campbell

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